Tag Archives: invertebrate

Endangered, Bird-eating Centipedes of Mauritius

Can a centipede really be endangered? Of course!

Centipedes don’t get much love, even from each other. They are solitary, irritable, fiercely cannibalistic, and arguably some of the most widely hated animals on earth. I know many biologists who would gladly handle a snake or tarantula, but shudder at the thought of a giant centipede creeping up their arm.

An Indopacific centipede, making good use of a hole in the wall. Photo by Thomas Brown, licensed under CC BY 2.0.

An Indopacific centipede, making good use of a hole in the wall. Photo by Thomas Brown, licensed under CC BY 2.0.

I never begrudge people for being scared of centipedes. They are objectively frightening: many-legged, venomous, fast-moving, and secretive. In the rural tropics, a painful bite from a giant centipede is a very real possibility. But none of this means they can’t be endangered, put at risk of extinction either by natural circumstance or by human activity.

Unsurprisingly, very few centipedes have ever been studied from a conservation-oriented perspective. Most of the time, there simply isn’t the funding, public interest, or lack of squeamishness to make that kind of research happen. There are, however, exceptions. Today I’m going to tell you about one: the giant centipedes of Mauritius and Rodrigues.

Mauritius, Rodrigues, and their satellites form a collection of tiny islands in the Indian Ocean, just a few thousand miles east of Madagascar. Like most islands they have a long, sad history of extinctions wrought by over-hunting, invasive species, and habitat destruction. The dodo bird, native to Mauritius, was one of the first victims.

Mauritius.png

Mauritius, in panoramic view. Photo by Clément Larher, licensed under CC BY-SA 3.0.

The two main islands are home to two species of giant centipede, the blue-legged (Scolopendra morsitans) and the Indopacfic (Scolopendra subspinipes) centipedes*. Both species are incredibly efficient predators, and with body lengths of 8 inches or more, they are more than capable of tackling large prey such as mice. On Mauritius, staple fare include house geckos and cockroaches, but they also take day-old chicks from their nests when opportunity strikes (Lewis et al. 2010). The Indopacific centipede can even swim, undulating side-to-side while holding its head above the surface like a crocodile (Lewis 1980).

Despite their size, venom, and general badassness, giant centipedes are prey for many larger animals. On Mauritius, they form 80% of the diet of feral cats that roam the island by night. The cats are apparently nimble (and daring) enough to tear apart the centipedes without getting bitten.

An Indopacific centipede from China. Photo by Thomas Brown, licensed under CC BY 2.0.

An Indopacific centipede from China. Photo by Thomas Brown, licensed under CC BY 2.0.

Even in the face of predation by cats, giant centipedes remained abundant until 1997, when a new invasive species came into the picture. That species was the musk shrew (Suncus murinus), introduced from India. A smaller shrew might become prey for a centipede, but the musk shrew is the largest in the world, reaching a length of 6 inches or more.

An 8-inch-long centipede is still a formidable adversary, but the shrews were used to encountering giant centipedes in their native range (as it happens, the Indopacific centipede also lives in India). They have made short work of centipede populations, which are now greatly reduced (Lewis et al. 2010). The Indopacific centipede is now found on Rodrigues, but no longer on Mauritius, while the blue-legged centipede is still found on both islands.

Mauritius and its satellite islands. From Lewis et al. (2010), licensed under CC BY 4.0.

Mauritius and its satellite islands. From Lewis et al. (2010), licensed under CC BY 4.0.

I am not about to launch into a passionate defense of blue-legged and Indopacific centipedes. As I said before, both species are abundant in tropical habitats all over the world, from Indonesia to the Caribbean. For all we know the centipedes themselves are invasive, dancing with cats and shrews on the graves of long-gone native species. Instead this article is about another giant, a third centipede, gone from Mauritius but still clinging to life on Serpent Island.

Serpent Island is a satellite of Mauritius, uninhabited by humans and with an area less than 100 acres. There is very little vegetation or soil there, and bare rock dominates the surface. In the absence of humans or large predators, sea birds thrive, especially sooty terns which nest by the thousands on open ground.

They share the space with centipedes — not Indopacific or blue-legged, but Serpent Island giant centipedes (Scolopendra abnormis), which are found on one other satellite island (Round Island) and nowhere else on earth — not even Mauritius. The centipedes are abundant on Serpent Island, with roughly 12 individuals per square meter. If centipedes frighten you, don’t plan your next vacation here.

During the day centipedes hide beneath rocky slabs and underground, away from the light and from watchful, easily enraged mother birds. Terns are active during the day, flying from land to sea and back again, gathering fish for their hungry chicks. With all the traffic, a centipede is better off staying out of sight.

A sooty tern. Photo by Duncan Wright, in public domain.

A sooty tern. Photo by Duncan Wright, in public domain.

By night the terns are less wary. Snakes, which would normally prey on tern chicks, are absent from the island, probably driven out soon after the arrival of European explorers. Without the competition, centipedes have risen to take their place. Wandering over the rocks, a centipede uses smell and touch to locate a nest, grab hold of a chick, and sink in its venom-laden fangs. More than any so-called bird-eating tarantula, the Serpent Island centipede is a true bird-eater. In captivity, they can survive for several years on a diet of chick legs (Lewis et al. 2010).

The taste for bird meat is probably a recent acquisition — Serpent Island centipedes most likely colonized the island only a few million years ago. They would have arrived from Mauritius, suggesting the larger island had a population of Serpent Island centipedes before they were driven to extinction by the introduced shrews, cats, and perhaps larger centipedes.

The Serpent Island centipede is classified as Vulnerable by the International Union for Conservation of Nature (IUCN 2012). This means the species is  “considered to be facing a high risk of extinction in the wild.” It is one of 10 potentially threatened centipedes on the IUCN Red List (of 3,300 total centipede species worldwide). So far, none have been given legal protection.

Centipede snacks. Photo by Duncan Wright, in public domain.

Centipede food. Photo by Duncan Wright, in public domain.

The bad news is that, if shrews or cats or rats were to be introduced to Serpent Island, the entire ecosystem would collapse. Invasive predators would quickly eat both chicks and centipedes, leaving Serpent Island a bare rock in the middle of the ocean, with a few tufts of grass and the occasional cockroach.

The good news is that centipedes are abundant in their last remaining habitats, with an estimated population of 10-15,000. Serpent Island is remote and protected, and biologists are pretty much the only visitors, so it is unlikely shrews will ever get there. The future of Serpent Island’s bird-eating centipedes is secure, for now.

Reminder: there are still 6 days left to donate to Dr. Adam Britton’s crowdfunding campaign to study threatened pygmy crocodiles in Australia! I’ve donated, and I encourage you to so if you think pygmy crocodiles, which you can read about here, are awesome, which of course they are. There are some amazing prizes for donors, including crocodile-themed artwork and jewelry!

*These species normally go by the common names Tanzanian giant (blue-legged) and Vietnamese giant (Indopacific). However, both are extremely wide-ranging in tropical habitats all over the world, including Hawaii where they have been introduced by humans (Shelley et al. 2014). To reduce confusion I used alternative common names.

Cited:

IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. Gland, Switzerland and Cambridge, UK: IUCN. iv + 32pp.

Lewis J.G.E., P. Daszak, C.G. Jones, J.D. Cottingham, E.Wenman, and A. Maljkovic. 2010. Field observations on three scolopendrid centipedes from Mauritius and Rodrigues (Indian Ocean) (Chilopoda: Scolopendromorpha). International Journal of Myriapodology 3: 123-137.

Lewis J.G.E. 1980. Swimming in the centipede Scolopendra subspinipes Leach (Chilopoda, Scolopendromorpha). Entomologists Monthly Magazine 116: 219-220.

Shelley R.M., W.D. Perreira, and D.A. Yee. 2014. The centipede Scolopendra morsitans L., 1758, new to the Hawaiian fauna, and potential representatives of the “S. subspinipes Leach, 1815, complex” (Scolopendromorpha: Scolopendridae: Scolopendrinae). Insecta Mundi 338: 1-4.

North America’s Big Five Centipedes

When Halloween comes around, snakes and spiders tend to steal the show. Yet centipedes, in my experience, tend to evoke even stronger reactions from people — I have met many entomologists who would happily handle a tarantula but recoil in horror when faced with a giant centipede.

In the United States there are five species of giant centipedes in the family Scolopendridae. Today, in the spirit of Halloween, I give you the Big Five: where they are found, what they do, and why I love them.

Blue Tree Centipede (Hemiscolopendra marginata)

The blue tree centipede. Photo by Sharon Moorman.

The blue tree centipede. Photo by Sharon Moorman.

This is the smallest of the five, seldom exceeding 3 inches, but still the largest centipede throughout most of its range. It is found through much of the East, from Ohio and Pennsylvania south to Florida and west to eastern Texas. Tree centipedes are also found in Mexico south to the Yucatan Peninsula. As the name suggests, the tree centipede is often an attractive blue-green, with yellow legs and orange fangs. The brightness of the color depends on the location, however, and some are paler than others.

The blue tree centipede is a habitat specialist, living under the bark of rotting trees, often before they have toppled to the ground. I have had the best luck finding them under the bark of pine logs. Because they are such good climbers, they occasionally wind up in buildings where they can cause quite a scare.

Bites from tree centipedes are painful but not much worse than a bee sting. They use their venom, as all centipedes do, to kill prey. Because they prefer to live in rotten pine logs, they may specialize in hunting beetle grubs that eat rotting wood. Like most centipedes, however, data on their feeding habits is severely lacking.

Green-striped Centipede (Scolopendra viridis)

The green-striped centipede is larger, reaching 6 inches or so, and usually pale yellow with a thick green or black stripe running down the back. Other patterns exist, however, and in parts of their range this species can appear more like a tree centipede or a tiger centipede (#4). These are adaptable centipedes, found from Florida west to Arizona, but don’t seem to venture further north than South Carolina.

The green-striped centipede. Photo by Jeff Hollenbeck, licensed under CC BY-ND-NC 1.0.

The green-striped centipede. Photo by Jeff Hollenbeck, licensed under CC BY-ND-NC 1.0.

Green-striped centipedes can live in a variety of habitats but they seem to prefer sandy forests. In Florida they can be found in scrub habitat, but like all centipedes they are not well-adapted to drought, and must stay moist by hiding underground or in rotting logs during the day.

Caribbean Giant Centipede (Scolopendra alternans)

The Caribbean giant is the only one of the Five with the russet-brown, mono-chromatic appearance of a “typical” centipede. It is probably our largest species, with a length easily exceeding 8 inches. However, the Caribbean giant is, as you might have guessed, a tropical centipede, and in the U.S. it lives only in southern Florida. It requires humid habitats, and the best place to find them is in and around the Everglades, in Dade and Monroe Counties.

A certain foreign species, the Vietnamese giant (Scolopendra subspinipes), is easily confused with the Caribbean giant at first glance. That wouldn’t be a concern, except that the Vietnamese giant has already become invasive in Hawaii and — this is just my speculating — is likely to become established in the Everglades at some point in the future. Because it is so large, often exceeding 10 inches, the Vietnamese giant is sometimes sold in the pet trade. Bites from either species are not deadly, but extremely painful.

Tiger Centipede (Scolopendra polymorpha)

A tiger centipede from Arizona. Photo by Sue Carnahan, licensed under CC BY-ND-NC 1.0.

A tiger centipede from Arizona. Photo by Sue Carnahan, licensed under CC BY-ND-NC 1.0.

Like the green-striped centipede, the tiger is a 6-inch-long animal found in a variety of habitats. Unlike the green-striped, this is a strictly western species, found from Idaho south through California into Mexico, and east all the way to Missouri. Its name comes from its color pattern: each segment is orange or yellow with a narrow, dark band.

Giant centipedes often move faster by undulating in a snake-like fashion, taking advantage of their long and muscular bodies. When a tiger centipede does this, the bands appear to “flicker,” rather like the brightly-banded milk snake and coral snake. This can make the centipede more difficult to track visually, and hence more difficult for a bird or mouse to grab.

Tiger centipedes, like their namesake, are voracious predators. They have been seen taking down prey much larger than themselves, including geckos and praying mantises. In turn, tiger centipedes are prey for scorpions, spiders, snakes, and many other predators.

A tiger centipede, fallen prey to a scorpion. Photo by Jasper Nance, licensed under CC BY-NC-ND 2.0.

A tiger centipede, fallen prey to a scorpion. Photo by Jasper Nance, licensed under CC BY-NC-ND 2.0.

Centipedes are adapted to moving fast, and their exoskeletons are thin and flexible. The drawback is that they dehydrate very easily. Although tiger centipedes are found in deserts, they still have to remain underground most of the time to conserve moisture.

Giant Desert Centipede (Scolopendra heros)

If you’ve ever seen centipedes used in a horror movie, they were probably heros*. They are big, reaching 8 inches or more. They are also brightly colored in black and orange — perfect for Halloween!

The Arizona form of the giant desert centipede. Photo by Aaron Goodwin, licensed under CC BY-ND-NC 1.0.

The Arizona form of the giant desert centipede. Photo by Aaron Goodwin, licensed under CC BY-ND-NC 1.0.

Heros are found in the desert Southwest, and color patterns vary by location. In eastern Texas and Oklahoma, they are typically jet-black with a bright orange head and yellow legs. In Arizona (above) they are usually red, with the first and last segments black. In New Mexico and western Texas the pattern is orange with black bands, much like a tiger centipede.

A giant desert centipede. Photo from NMNH Insect Zoo, licensed under CC BY-NC 2.0.

A giant desert centipede. Photo from NMNH Insect Zoo, licensed under CC BY-NC 2.0.

Why have black on just the head and the last segment? This an example of automimicry, in which one part of an animal’s body mimics the other. In this case, the tail-end of the giant desert centipede mimics its head-end. When faced with a giant centipede, predators usually attack the head, hoping to avoid a painful bite. If a predator gets confused, however, and attacks the tail instead, an unpleasant surprise awaits when the true head whips around to greet its attacker.

Centipedes, giant and otherwise, are pretty scary, and I never begrudge people who are afraid of them. Still, centipedes are amazing animals and if you see one, I encourage you to take a closer look. It will teach you, if nothing else, that just because an animal is frightening does not mean it can’t be beautiful.

*There is a centipede in one of the Human Centipede movies. People often tell me this after I tell them I study centipedes, so let me clarify a few things: I don’t know what kind of centipede the bad guy has for a pet. Not because I couldn’t identify it, but because I have never watched those movies and never will. I also don’t want to hear you describe your favorite scene with as many details as possible. Thank you.

The Scaly Crickets

by Joseph DeSisto

Among many new species named today, some of the most unusual were three new crickets from Southeast Asia (Tan et al. 2015). These crickets belong to the obscure and poorly-known family Mogoplistidae, cousins to the more recognizable (and audible) field crickets (Gryllidae). They look like field crickets too, except that their bodies are covered in scales.

A scaly cricket (Arachnocephalus vestitus). © Entomart.

A scaly cricket (Arachnocephalus vestitus). © Entomart.

When you touch a butterfly’s wings, you might notice a fine, powdery substance rubbing off on your fingers. The powder is made up of microscopic scales, which cover the wings of butterflies and moths. Scales give the wings their color, but they also provide insulation and protect the wings during flight. Perhaps most importantly, scales can fall off and make the wings slippery. This allows butterflies and moths to evade a careless hand as easily as a wet bar of soap.

The scientific name for butterflies and moths is Lepidoptera, which translates to “scaly wing” — scales are one of the most important features defining the group. However, many other groups of insects also have scales. Mosquitoes and silverfish have them, and so do scaly crickets.

The scales of a scaly cricket (Ornebius formosanus). Figure from Yang and Yen (2001), licensed under CC BY 2.0.

The scales of a scaly cricket (Ornebius formosanus). Figure from Yang and Yen (2001), licensed under CC BY 2.0.

Cricket scales, like those of butterflies and mosquitoes, are microscopic, powder-like, and easily shed. To really appreciate their beauty, a scanning electron microscope is needed. The first look came in 2001, when Yang and Yen published the first high-resolution images of cricket scales.

Aside from being scaly, scaly crickets aren’t all that unusual. They are adaptable, able to eat decaying plants as well as other insects, and they tend to live in moist sandy habitats. No scaly crickets are capable of flight, and females lack wings entirely, but the males do have small wings which they rub together to make chirping sounds (Love and Walker 1979). Click on the audio file below to listen to an amorous male scaly cricket (recorded by Thomas J. Walker).

Of the three new species, two were found in the Sakaerat Biosphere Reserve, in Thailand. This reserve consists mainly of high-altitude dry forest, with a few grasslands, and is home to many endangered species including tigers and giant black squirrels.

The third cricket is native to Pulau Ubin, an island off the coast of Singapore. Pulau Ubin is one of the last remaining wild areas in the already tiny country. Singapore’s government has been eager to develop portions of the island, but in recent years tourism has become more profitable. Fear of losing foreign visitors has encouraged officials to protect, rather than level, valuable habitat. For now, the status of the new scaly crickets appears secure, but in rapidly urbanizing Southeast Asia, nothing is certain.

A scaly cricket (Mogoplistes brunneus). © Entomart.

A scaly cricket (Mogoplistes brunneus). © Entomart.

Cited:

Love R.E. and T.J. Walker. 1979. Systematics and acoustic behavior of scaly crickets (Orthoptera: Gryllidae: Mogoplistinae) of eastern United States. Transactions of the American Entomological Society 105:

Tan M.K., P. Dawwrueng, and T. Artchawakom. 2015. Contribution to the taxonomy of scaly crickets (Orthoptera: Mogoplistidae: Mogoplistinae). Zootaxa 4032(4): 381-394.

Yang J. and F. Yen. 2001. Morphology and character evaluation of scales in scaly crickets (Orthoptera: Grylloidea: Mogoplistidae). Zoological Studies 40(3): 247-253.

Why Scorpion Venom is So Complex

by Joseph DeSisto

Scorpion venom, like many animal venoms, is incredible complex. It is made up of hundreds of different toxins and other proteins, each with a specific function, all mixed together in a lethal cocktail. Why do scorpions need so many different toxins? Last week, scientists at the Chinese Academy of Sciences published the results of their attempt to answer this question (Zhang et al. 2015).

They began by studying a particular class of proteins found in scorpion venom, which work by attacking the sodium ion-channel proteins in their victims.

The stripe-tailed scorpion, Vaejovis spinigerus, ready for action.. Photo by Joseph DeSisto.

The stripe-tailed scorpion, Vaejovis spinigerus, ready for action. Photo by Joseph DeSisto.

Sodium ion-channels help regulate the amount of sodium inside animal cells, which is vital for cells to function properly. In nerve cells, they are even more important: the change in sodium concentration inside and outside the cell is what transmits electric signals.

Toxins that inhibit sodium channels prevent the nervous system from working, which leads to death if the victim is small (like an insect). Scorpions have toxins called sodium-channel toxins to do exactly that. The puzzle is, scorpions have many different genes that produce sodium-channel toxins, each of which has a slightly different structure.

All proteins are essentially strings that are wound, twisted, and tied into a specific structure. The structure of a protein is critical to its function, since proteins need to have certain shapes in order to interact with each other like a lock and key. All sodium-channel toxins have a portion designated as the “interactive region” — the key — which attaches to a series of loops on the prey’s sodium ion-channel (the lock). If the key fits and the connection is successful, the prey’s ion-channel can no longer function.

A mother stripe-tailed scorpion, carrying young. Photo by Joseph DeSisto.

A mother stripe-tailed scorpion, carrying young. Photo by Joseph DeSisto.

Zhang and his colleagues studied the genome of their scorpion, a desert-dwelling East Asian species known as the Chinese golden scorpion (Mesobuthus martensii). They found no less than 29 different genes coding for sodium channel toxins.

There was a time, perhaps hundreds of millions of years ago, when scorpions only had one gene for sodium-channel toxins. Eventually that gene was duplicated, and thereafter the scorpion genome had multiple copies of the same toxin-producing gene. Since then, each copy of the gene has continued to mutate and evolve in its own direction. Now each toxin, despite having the same basic structure, is just a little bit different from the rest.

As it happens, the genes for sodium ion-channels in a scorpion’s prey also exist in multiple copies, each with minor variations. Zhang and colleagues hypothesized that scorpions need so many varieties of toxins because each toxin can only interact with a specific variety of ion-channel. In other words, scorpion venom needs lots of different keys because the prey have so many different locks.

To test this, the scientists examined the different toxin-gene copies to better understand how they had evolved. Sure enough, the “interactive region,” the key, of each toxin had mutated and evolved much more quickly than the “body” of the toxin. This provided strong evidence that natural selection has caused scorpion venom to evolve different types of toxins to keep up with the ever-evolving ion-channels in their prey.

Scorpions are incredible animals for so many reasons. They have been around for more than 400 million years — as long as there have been insects to hunt on land, scorpions have been there to hunt them. They are amazing and diverse in form, lifestyle, and hunting strategy. How fitting that they should be just as amazing on the molecular level.

Cited:

Zhang S., B. Gao, and S. Zhu. Target-driven evolution of scorpion toxins. Nature Scientific Reports 5:14973 doi: 10.1038/srep14973

Shrimp-like Amphipods found in Sea Anemones

by Joseph DeSisto

Amphipods are crustaceans, similar to tiny shrimp. There are around 10,000 known species, with more being discovered each year. Most amphipods are marine and live as scavengers or predators, swimming or scuttling after tiny particles of food or plankton. A few are predatory, and use mantis-like front legs to snap up smaller creatures.

Stenothoe marina, related to the newly described amphipods. Photo by Hans Hillewaert, licensed under CC BY-SA 4.0.

Stenothoe marina, related to the newly described amphipods. Photo by Hans Hillewaert, licensed under CC BY-SA 4.0.

Last week’s new species are even more bizarre: they are “associates” living on the bodies of larger animals, ranging from sea anemones to mussels to hermit crabs (Krapp-Schickel and Vader 2015). So what exactly are they doing there?

Anemone-dwelling amphipods spend their time clambering over the tentacles of their host. Sea anemone tentacles are covered in microscopic stingers, to which the amphipods (like clown fish) are immune. Being surrounded by venomous tentacles might protect the amphipods from larger predators.

In turn, amphipods probably scavenge bits of detritus, such as uneaten prey, off the body of the anemone. One amphipod, however, does things a little differently. Instead of scavenging, it lives as a parasite, feeding on the flesh of its sea anemone host (Moore et al. 1994). Regardless, all of these amphipods have grasping, hook-like front legs called gnathopods (silent G), which they use to climb over and within the bodies of other animals.

Sea anemones. Photo by Francois Guillon, licensed under CC BY-SA 4.0.

Sea anemones. Photo by Francois Guillon, licensed under CC BY-SA 4.0.

Mussel-associated amphipods are more peaceful, but not entirely welcome, guests. Mussels are filter-feeders that extract plankton from the water, so instead of eating the mussel, amphipods steal some of the daily plankton catch (Tandberg et al. 2010). They are kleptoparasites, animals that steal their food.

Mussel-dwellers belong to the genus Metopa, and have surprisingly sophisticated lives (Tandberg et al. 2010). Each mussel is home to a single mating pair of adult amphipods, who defend their home against intruders. Most species spend their entire adult lives within the shell of a single mussel. In this time they work hard to raise multiple generations, which grow together until they are ready to head out to sea and find molluscan homes of their own.

A common hermit crab, host to a unique amphipod. Photo © Biopix: N Sloth, licensed under CC BY-NC 3.0.

A common hermit crab, host to a unique amphipod. Photo © Biopix: N Sloth, licensed under CC BY-NC 3.0.

Still other amphipods are described as hermit crab associates, some living on the crab’s acquired snail shell (Krapp-Schickel and Vader 2015). At least one species eats invertebrates that land and begin to grow on the shell. Others, however, live on the bodies of the crabs themselves.

This seems like a risky move. Hermit crabs are rigorous self-cleaners, constantly scrubbing the insides of their shells with specialized, brush-like hind legs. Perhaps the amphipods, by scavenging bits of uneaten food from the crab’s body, are helpful maids to their type-A hosts. If this is the case, hermit crabs may spare their amphipod companions on purpose. We still don’t know if the crab-dwelling amphipods are helpful cleaners or true parasites — if the latter is true, they must be well-adapted to avoid detection by their hosts.

Cited:

Krapp-Schickel T. and W.J.M. Vader. 2015. Stenothoids living with or on other animals (Crustacea, Amphipoda). Zoosystematics and Evolution 91(2): 215-246.

Moore P.G., P.S. Rainbow, and W. Vader. 1994. On the feeding and comparative biology of iron in coelenterate-associated gammaridean Amphipoda (Crustacea) from N. Norway. Journal of Experimental Marine Biology and Ecology 178: 205-231.

Tandberg A.H.S., C. Schandler, and F. Pleijel. 2010. First record of the association between the amphipod Metopa alderi and the bivalve Musculus. Marine Biodiversity Records 3, e. 5, 2 pp.

Sea Spiders and the Rise of the Chelicerates

by Joseph DeSisto

Sea spiders are small, eight-legged marine arthropods with a vaguely spider-like appearance: members of the obscure class Pycnogonida. Most of the 1300 or so species are predatory, feeding on jellyfish, sponges, and other soft-bodied marine invertebrates. After eight-leggedness and predatory habits, the similarities with spiders end.

A yellow-kneed sea spider. Photo by Sylke Rohrlach, licensed under CC BY-SA 2.0.

A yellow-kneed sea spider. Photo by Sylke Rohrlach, licensed under CC BY-SA 2.0.

So what exactly are sea spiders? For a long time they were considered to be the most ancient members of an already-ancient group of animals: the Chelicerata, which includes the arachnids and the horseshoe crabs (Dunlop and Arango 2005). These animals are united by their possession of chelicerae, a kind of mouthpart.

Chelicerae are extremely versatile, and in the 450-odd million years they’ve been around, natural selection has resulted in a huge diversity of forms. A spider’s chelicerae, for example, are hollow and capable of injecting venom into prey. Scorpion chelicerae, on the other hand, are smaller and used for chewing up food. Some harvestmen (daddy-long-legs) have long chelicerae with pincers at the end, useful for grabbing prey.

Sea spiders have chelicerae too — sort of. Their mouthparts at least are similar to chelicerae, but because they’ve been subject to hundreds of millions of years of evolution, it isn’t easy to discern their “true” identity. Modern sea spiders have hollow, tube-like chelicerae, which they use to suck out the insides of their prey.

 licensed under CC BY-SA 4.0.

A sea spider using its chelicerae to prey on a hydroid. Photo by Bernard Picton, licensed under CC BY-SA 4.0.

Classification can get complicated. To understand where sea spiders fit into the tree of life, we must ask the question: are sea spider chelicerae “real” chelicerae? That might sound like a silly question — after all, “chelicerae” is just a term we made up. But what we really mean is, are sea spider chelicerae homologous with the chelicerae of arachnids and horseshoe crabs? If they are, then sea spiders and the other chelicerates inherited their mouthparts from the same common ancestor. If not, chelicerae evolved twice: once in sea spiders, and separately in the “true” Chelicerata.

In 2005, Amy Maxmen and colleagues carefully studied the chelicerae of sea spiders and found that they emerged from a different part of the body than in other arthropods. It seemed that in sea spiders, chelicerae emerged from the same segment that contained the eyes (but not mouthparts) in other chelicerates. This suggested that sea spiders were not true chelicerates, but instead formed their own group, which Maxmen et al. (2005) hypothesized to be the oldest living arthropod lineage.

A sea spider -- the red hanging structure contains the mouthparts. Photo by Scott C. France, licensed under CC BY-SA 2.0.

A sea spider — the red hanging structure contains the mouthparts. Photo by Scott C. France, licensed under CC BY-SA 2.0.

In arthropods and other segmented animals, Hox genes are responsible for making sure that all the right body parts develop on all the right segments. It was surprising, then, when a 2006 study found that the Hox genes place chelicerae on the same segments in sea spiders and in arachnids (Jager et al. 2006). Apparently, this segment was shifted backwards in sea spiders, creating confusion.

Over the years, scientists have tried comparing the DNA of many arthropods to try and understand how they are related to one another. One of the most comprehensive studies (Regier et al. 2010) placed sea spiders comfortably within the Chelicerata, as the group’s oldest (i.e., basal-most) lineage. Since then there has been little debate: sea spiders may be some of the oldest arthropods on earth, but they really are chelicerates, after all (Giribet and Edgecombe 2012). That is, until new evidence comes along to shake things up again.

Cited:

Dunlop J.A. and C.P. Arango. 2005. Pyncogonid affinities: a review. Journal of Zoological Systematics and Evolutionary Research 43(1): 8-21.

Giribet G. and G.D. Edgecombe. 2012. Reevaluating the arthropod tree of life. Annual Review of Entomology 57: 167-186.

Jager M., J. Murienne, C. Clabaut, J. Deutsch, H. Le Guyader, and M. Manuel. 2006. Homology of arthropod anterior appendages revealed by Hox gene expression in a sea spider. Nature 441: 506-508.

Maxmen A., W.E. Browne, M.Q. Martindale, and G. Giribet. Neuroanatomy of sea spiders implies an appendicular origin of the protocerebral segment. Nature 437: 1144-1148.

Regier J.C., J.W. Schultz, A. Zwick, A. Hussey, B. Ball, R. Wetzer, J.W. Martin, and C.W. Cunningham. 2010. Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences. Nature 463: 1079-1083.

Are Tarantulas Dangerous? Most Aren’t, A Few Might Be

Of the 900 or so known tarantula species, almost all are harmless (Isbister et al. 2003, Lucas et al. 1994). A bite by any large spider can be painful even if no venom is injected, since the fangs themselves are essentially big needles. Even if venom is injected, however, most tarantula bites result in little more than local pain and swelling. When there are medical problems, the cause is usually shock or an allergic reaction, rather than the action of the venom itself.

The Chilean rosehair tarantula (Grammostola rosea), a hardy and docile pet. Photo from Insects Unlocked, in public domain.

The Chilean rosehair tarantula (Grammostola rosea), a hardy and docile pet. Photo from Insects Unlocked, in public domain.

That said, not all tarantulas are equally venomous. The most common tarantulas sold in pet shops are all pretty benign: the Chilean rose hair, the Mexican redknee, and the pinktoe tarantulas have both mild venom and docile habits. They can be handled gently with almost no risk of being bitten.

Other, more exotic species kept by seasoned tarantula experts include the cobalt blue, the goliath birdeater, and the golden starburst tarantulas. These are beautiful and impressive captives — the goliath birdeater can attain a 12-inch leg span. The cobalt blue and golden starburst are stunningly colorful animals, the latter approximately matching the color of Donald Trump’s hair. These species are also more nervous and willing to bite, and their bites are generally more painful (e.g., Takaoka et al. 2001).

The golden starburst tarantula (Pterinochilus murinus), guarding its silken retreat. Photo by Stefan Walkowski, licensed under CC BY-SA 3.0.

A golden starburst tarantula (Pterinochilus murinus) guarding its silken retreat. Photo by Stefan Walkowski, licensed under CC BY-SA 3.0.

Avid tarantula enthusiasts don’t get most of their spiders from pet shops. Instead they buy tarantulas from other spider-keepers who breed their pets, or from companies that import spiders and other animals from around the world. With international trade, hundreds of species are available for hobbyists collect. Many of these are poorly known, most have not had their venom studied, and a few haven’t even been formally described by scientists.

Where venomous animals are concerned, gaps in scientific knowledge can have serious consequences. A few years ago a Swiss man was bitten by one of his many pet tarantulas — at first, the only symptoms were mild pain, hot flushes and sweating. He brought himself to the hospital 15 hours later, when he began to experience severe muscle cramps and stabbing chest pain. Doctors gave him medication (midazolam and lorazepam) that reduced the symptoms, but muscle cramps did not disappear completely until three weeks after the bite (Fuchs et al. 2014). The tarantula in this case was a regal ornamental tarantula, a magnificent tree-dwelling spider native to India.

A regal ornamental tarantula (Poecilotheria regalis). Photo by Morkelsker, in public domain.

A regal ornamental tarantula (Poecilotheria regalis), with a leg span up to 6 inches. Photo by Morkelsker, in public domain.

There are at least 16 species of ornamental tarantulas, all from tropical forests in India and Sri Lanka. Most of them can be found in the exotic pet trade, and many have become popular with tarantula keepers looking for something a little more exciting. Exciting is certainly what they get: ornamental tarantulas are stunningly beautiful, as well as extremely fast and agile climbers. They are also quick to bite if cornered. Ornamental tarantula venom, while not deadly, is certainly underestimated.

To see if muscle cramps and chest pain were common symptoms of ornamental tarantula bites, Joan Fuchs and colleagues (2014) looked at 26 case reports, most of which were blog entries by seasoned tarantula keepers and breeders. Of the cases, 58% involved muscle cramps, along with other symptoms such as fever and heavy breathing. A few patients even lost consciousness for short periods. All bites were painful, but those that led to muscle cramps were severely so. This led the researchers to believe that, in cases where muscle cramps did not appear, the spider had simply injected much less venom.

The metallic ornamental tarantula (Poecilotheria metallica). Photo by Søren Rafn, licensed under CC BY-SA 3.0.

The metallic ornamental tarantula (Poecilotheria metallica). Photo by Søren Rafn, licensed under CC BY-SA 3.0.

It’s worth remembering that no tarantula bite has ever been fatal. It is a sorry fact, however, that by far the greatest source of knowledge on tarantula bites comes not from scientists, but from spider-keepers who take great pains (literally) to record their symptoms after every bite. This information is shared with other spider-keepers online at websites like Arachnoboards, so other hobbyists know what to expect from each species.

Such informal reports have been done for many species that have yet to be studied closely by scientists, and some that haven’t even been “discovered” (i.e., been given Latin names and formally described). The scientific axiom that “more work is needed” may be a cliché, but regarding tarantula bites and spider venom in general, it is certainly true.

Cited:

Fuchs J., M. von Dechend, R. Mordasini, A. Ceschi, and W. Nentwig. 2014. A verified spider bite and a review of the literature confirm Indian ornamental tree spiders (Poecilotheria species) as underestimated theraphosids of medical importance. Toxicon 77: 73-77.

Isbister G.K., J.E. Seymour, M.R. Gray, and R.J. Raven. 2003. Bites by spiders of the family Theraphosidae in humans and canines. Toxicon 41(4): 519-524.

Lucas S.M., P.I. Da Silva Júnior, R. Bertani, and J.L. Cardoso. 1994. Mygalomorph spider bites: a report on 91 cases in the state of São Paulo, Brazil. Toxicon 32(10): 1211-1215.

Takaoka M., S. Nakajima, H. Sakae, T. Nakamura, Y. Tohma, S. Shiono, and H. Tabuse. 2001. Tarantulas bite: two case reports of finger bites from Haplopelma lividum. The Japanese Journal of Toxicology 14(3): 247-250.

Deadly Caterpillars

by Joseph DeSisto

Today’s article is about the hemileucines, caterpillars with venom-injecting spines. While most have harmless, if painful, stings, a few have venom powerful enough to kill an adult human. But before things get too dark, let’s take some time to appreciate some harmless little beasties:

First-instar caterpillars of the io moth (Automeris io), munching on some oak leaves. Photo by Shawn Hanrahan, licensed under CC BY-SA 2.5.

First-instar caterpillars of the io moth (Automeris io), munching on some oak leaves. Photo by Shawn Hanrahan, licensed under CC BY-SA 2.5.

These are the newly-hatched caterpillars of the io moth, found in eastern and central North America. As caterpillars, they like to move and feed in groups, which provides some protection against predators. The moth, with a wingspan approaching four inches, looks like this:

An adult io moth, ready to take flight and find a mate. Photo by Patrick Coin, licensed under CC BY-SA 2.5.

An adult io moth, ready to take flight and find a mate. Photo by Patrick Coin, licensed under CC BY-SA 2.5.

Not bad, right? Sadly, for all its showy appearance, io moths don’t have mouthparts and cannot feed as adults. A lucky moth dies when its energy reserves run out after about a week, if it can manage to avoid being snapped up by bats, spiders, and other hunters.

This has its benefits — a moth with no appetite can spend its time and energy mating and laying eggs as much as possible. It also has consequences — the caterpillars, to prepare for the most important week of their lives, have to eat a lot. Within a few weeks of devouring as much greenery as physically possible, an io caterpillar can go from being a half-inch-long worm to a nearly three-inch-long monstrosity, brilliant green with red and white racing stripes:

An io moth caterpillar, almost ready to spin a coccoon. Photo by Tim Lethbridge, licensed under CC BY-ND-NC 1.0.

An io moth caterpillar, almost ready to spin a coccoon. Photo by Tim Lethbridge, licensed under CC BY-ND-NC 1.0.

See the spiky, poisonous-looking tufts growing out of the caterpillar’s back and sides? Io caterpillars are indeed capable, and more than willing, to deliver a painful sting. If you brush up against these spines, the tips will break off and start to inject venom. It’s not nice, but not much worse than an encounter with stinging nettle plants which, incidentally, uses many of the same toxins. The strategy is shared by other hemileucine caterpillars, among which are some of the largest and most conspicuous moths in North America.

Southern Brazil has its own hemileucines, including members of the genus LonomiaLonomia moths are large and attractive, if perhaps a bit less flashy than their northern brethren:

An adult Lonomia moth from Brazil. Photo by Benjamint, licensed under GFDL 1.2.

An adult Lonomia moth from Brazil. Photo by Benjamint, licensed under GFDL 1.2.

Their caterpillars, too, are less conspicuous, which is why they sometimes wind up stinging people. A single sting contains only a miniscule amount of venom — not nearly enough to do any real harm. The problem comes from the fact that hemileucine caterpillars tend to feed in groups. If a person accidentally brushes up against 20 or more Lonomia at the same time, the result can be severe.

Unlike the io caterpillar, Lonomia has venom designed to do more than just irritate the skin. As soon as it enters the bloodstream, anticoagulants work to prevent the blood from clotting, while other proteins punch holes in the victim’s blood vessels. The result is violent internal bleeding. In the worst cases, death is usually the result of internal bleeding in the brain (Pinto et al. 2010).

Each of these spines contains a tiny amount of venom. Photo from Centro de Informações Toxicológicas de Santa Catarina, in public domain.

Each of these spines contains a tiny amount of venom. Photo from O Centro de Informações Toxicológicas de Santa Catarina, in public domain.

Over the last few decades, cases in southern Brazil have been on the rise, and scientists at the Butantan Institute in São Paulo have been studying the molecular aspects of Lonomia venom. The most important result is that Brazilian hospitals now have access to an antivenom that quickly halts the venom’s action.

To North Americans a venomous caterpillar, even a deadly one, might seem like an esoteric problem. Yet in parts of southern Brazil, the caterpillar causes more medical emergencies than any snake, spider, or scorpion (Pinto et al. 2010). The Brazilian Ministry of Health estimated that in 2008, for every 100,000 people in the caterpillar’s range, there were eight stings. Meanwhile, incidents have become more common as rain forest has been replaced by fruit tree plantations, which happen to provide ideal habitat for Lonomia, and the stage for deadly encounters.

A cluster of Lonomia obliqua caterpillars. Photo from Photo from O Centro de Informações Toxicológicas de Santa Catarina, in public domain.

A cluster of Lonomia obliqua caterpillars. Photo from O Centro de Informações Toxicológicas de Santa Catarina, in public domain.

Cited:

Pinto A.F.M., M. Bergerm J. Reck, R.M.S. Terra, and J.A. Guimaraes. 2010. Lonomia obliqua venom: In vivo effects and molecular aspects associated with the hemorrhagic syndrome. Toxicon 56(7): 1103-1112.

Saving the Easter Island Springtails

by Joseph DeSisto

By the time European settlers reached tiny Easter Island (Rapa Nui), far off the Pacific coast of Chile, it was already in ecological turmoil. The island had first been colonized by Polynesians as late as 1200 B.C.E. — their descendents comprise the Rapa Nui people, now the island’s indigenous population. They had at least 500 years before European colonization, and in that time the Rapa Nui people did great things — they constructed the world-renowned moai statues, for example:

Fifteen maoi -- on average, each of these is 13 feet tall and weighs 14 tons, but many are much larger. Photo by Ian Sewell, licensed under CC BY-SA 3.0.

Fifteen maoi — on average, each of these is 13 feet tall and weighs 14 tons, but many are much larger. Photo by Ian Sewell, licensed under CC BY-SA 3.0.

Despite the grandeur of the sometimes 30-foot-high moai, Easter Island already had its own wonders — the island was dominated by a species of palm tree, with trunks easily large enough to make a sea-faring canoe. That palm tree (Paschalococos disperta) existed only on Easter Island. I wish the picture below showed one of these trees, but that would be impossible — the Easter Island palm has been extinct for centuries. When European settlers arrived in 1722, the island was already almost completely deforested, with just a few pockets of forest left. Over the next few centuries, intensive sheep-grazing sealed the palm’s fate.

The Chilean wine palm (Jubaea chilensis) is the Easter Island palm's closest living relative. Photo by Scott Zona, licensed under CC BY 2.0.

The Chilean wine palm (Jubaea chilensis) is the extinct Easter Island palm’s closest living relative. Photo by Scott Zona, licensed under CC BY 2.0.

Today, the only evidence that palms ever existed on Easter Island come from petrified pollen grains and nut fragments (Flenley et al. 2006). The microscopic pollen grains are virtually indestructible and, in a cruel irony, have long outlasted the shepherds and, indeed, many of the moai themselves.

After such an environmental tragedy, it would be surprising to find any new species on Easter Island. And yet, even though every native vertebrate and many native plants have been driven to extinction, invertebrates that live exclusively on Easter Island continue to be discovered.

Just last week, biologists Taiti and Wynne (2015) published a survey of the woodlice (i.e., roly-polies) of the island, documenting two new species, one of which is only known from Easter Island. And that’s not all — a few months ago, five new springtails were introduced to science, unique to Easter Island (Bernard et al. 2015). Springtails are tiny, near-microscopic insect relatives that move by leaping extraordinary distances — if woodlice are the bumper-cars, then springtails are the bunnies of the micro-scape.

In profile: two new woodlouse species from Easter Island. Photo from Taiti and Wynne (2015), licensed under CC BY 3.0.

Two new cave-dwelling woodlouse species from Easter Island: Styloniscus manuvaka (left) and Hawaiioscia rapui (right). Photo from Taiti and Wynne (2015), licensed under CC BY 3.0.

So where are all these new species coming from? It turns out that even in such a desolate place as Easter Island, where almost all native wildlife and flora are gone, caves continue to provide a haven for undiscovered species (Wynne et al. 2014). All eight of these new species were found deep in caves, where humans have had less impact.

This is good news for those woodlice and springtails — now that we know they exist, perhaps we can keep them from following so many of their surface-dwelling brethren into extinction. After all, caves may be isolated, but they are not immune to our footprints. Keeping human traffic away from caves, and making sure the surrounding fern-moss habitat stays healthy, are both steps in the right direction (Wynne et al. 2014).

As a species, we have all but destroyed Easter Island’s fragile and unique ecosystems. Even so, in spite of our best efforts, a few native species, deep in the unexplored reaches of caves, persist. There is hope for them — and us — yet.

Cited:

Bernard E.C., F.N. Soto-Adames, and J.J. Wynne. 2015. Collembola of Rapa Nui (Easter Island) with descriptions of five endemic cave-restricted species. Zootaxa 3949(2): 239-267.

Flenley J.R., A.S.M. King, J. Jackson, C. Chew, J.T. Teller, and M.E. Prentice. 2006. The Late Quaternary vegetational and climatic history of Easter Island. Journal of Quaternary Science 6(2): 85-115.

Taiti S. and J. Wynne. 2015. The terrestrial Isopoda (Crustacea, Oniscidea) of Rapa Nui (Easter Island), with descriptions of two new species. ZooKeys 515: 27-49.

Wynne J.J., E.C. Bernard, F.G. Howarth, S. Sommer, F.N. Soto-Adames, S. Taiti, E.L. Mockford, M. Horrocks, L. Pakarati, and C. Pakarati-Hotus. 2014. Disturbance relicts in a rapidly changing world: The Rapa Nui (Easter Island) factor. BioScience 64: 711-718.

Rat Lungworm Disease: How it Works

by Joseph DeSisto

Rat lungworm disease — even the name sounds awful. But to understand the disease, we first have to understand the life cycle of the worm that causes it which, incidentally, is as fascinating as it is terrifying.

The rat lungworm (Angiostrongylus cantonensis) is a kind of parasitic roundworm or nematode which, unsurprisingly, is mainly a parasite of rats. It’s favorite host is the brown “Norway” rat, now found throughout the world where it has been spread by human travels. The worms enter a rat as larvae less than a millimeter long, first entering the bloodstream and then migrating, like salmon up a stream, to the host’s brain. Here they gorge themselves with brain tissue until they become sub-adults. The brain-filled, sub-adult lungworms are almost half an inch in length — and still not done growing.

The brown rat, common in cities, is the primary host of the rat lungworm. Photo by  Ian Kirk, licensed under CC BY 2.0.

The brown rat (Rattus norvegicus), common in cities, is the primary host of the rat lungworm. Photo by Ian Kirk, licensed under CC BY 2.0.

Before they reach adulthood, the worms migrate again via the circulatory system, this time stopping when they reach the heart’s right ventricle, or the pulmonary arteries. In the heart tissue, the worms finally mature, mate, and lay their eggs — but the eggs, too, must migrate. The eggs are laid directly into the bloodstream, and because the pulmonary arteries lead directly to the lungs, that’s where the eggs end up. Hence, the name “lungworm,” even though they might as well be called “heartworms” or even “brainworms.”

Even now, the lungworms have yet to finish their ricochet across your — I mean, the rat’s — body systems. When the eggs hatch, baby worms travel up the respiratory tract, leaving the lungs and entering the esophagous, where they enter the digestive system.

An adult female rat lungworm. Photo from Lindo et al. (2002), in public domain.

An adult female rat lungworm. Photo from Lindo et al. (2002), in public domain.

Despite being microscopic, the baby lungworms are extremely tough. They have to be, because they are going all the way, from throat to stomach to intestines and beyond. Finally, when the rat defecates, its feces are loaded with baby lungworms, all ready to start infectious lives of their own.

If they are lucky, the scent of rat dung will catch the nose of a passing snail or slug. Land snails are usually scavengers that will eat almost any non-living biological material, from dead leaves to carrion to, yes, dung. Should a snail care to take a bite, it will quickly become infected with hordes of developing lungworms.

As any city-dweller will attest, rats will eat almost anything, including, it just so happens, snails. The life cycle of the rat lungworm continues with a rat eating an infected snail or slug, and with the worms travelling up to the rat’s brain to eat, grow, and make wormy babies of their own. For a more technical description of the rat lungworm and its strange life cycle, I recommend Cowie’s 2013 review paper.

The gray garden slug, which has been recorded as an intermediate host for the rat lungworm. In other words, if you eat them, cook them first. Photo by Bruce Marlin, licensed under CC BY-SA 3.0.

The gray garden slug (Deroceras reticulatum), which has been recorded as an intermediate host for the rat lungworm. In other words, if you eat them, cook them first. Photo by Bruce Marlin, licensed under CC BY-SA 3.0.

Rat feces aren’t just eaten by snails, and snails aren’t just eaten by rats. As a result, rat lungworms accidentally infect animals they aren’t supposed to, such as flatworms, shrimp, frogs, birds and, yes, humans. People all over the world eat snails, both on purpose and by accident. Rat lungworm disease in China is usually attributed to eating market-bought raw snails (Lv et al. 2008). During a 2002 outbreak in Jamaica, where snails aren’t as popular, infections were the result of contaminated vegetables (Lindo et al. 2002).

Eating cooked snails is fine, since the cooking process kills the lungworm larvae — it’s raw escargot that can cause problems. Snails and slugs in gardens can also leave a trail of worm larvae in their slime, so washing vegetables in lungworm-inhabited areas can be important.

What happens when a person accidentally eats a rat lungworm? In a human, the worm follows the same cycle as it does when in a rat, going from circulatory to nervous to circulatory to respiratory to digestive systems, and back out to be eaten again by snails.

A summary of the rat lungworm life cycle (click to enlarge). Figure from the Centers for Disease Control and Prevention, in public domain.

A summary of the rat lungworm life cycle (click to enlarge). Figure from the Centers for Disease Control and Prevention, in public domain.

Medical problems come from the sub-adult worms, as they eat away at the host’s brain tissue. Worms are pretty big things to have squirming around in your head, and as they burrow through nervous tissue, they can cause enough damage that the brain becomes inflamed. The result is eosinophilic meningitis, a series of symptoms of which lungworms are just one possible cause. In some cases the damage can cause behavioral changes in the host — one victim developed severe photophobia, and was terrified of light (Ramirez-Avila et al. 2009).

Rat lungworm disease is not common but can be serious, and potentially fatal. Most cases occur in the tropics, especially in Southeast Asia and the Pacific, where the worm is native. Recently, however, lungworms have become more common across the world, as rats and certain snails have been introduced by humans (Kliks and Palumbo 1992).

A small outbreak in Hawaii occurred only a decade ago (Hochberg et al. 2007) and made the news. Global trade in food has also been a factor — the contaminated vegetables that caused the outbreak in Jamaica may very well have been grown halfway around the world (Lindo et al. 2002). As the world becomes economically smaller, strange local diseases can become worldwide problems.

And yet, for all this gloom and doom, the reason I wrote this article in the first place is that the rat lungworm is actually a pretty cool animal. It’s easy to view wormy parasites like nematodes as simple and unsophisticated creatures. But if the rat lungworm can teach us anything, it’s that even “simple” animals can have incredibly complex and, yes, amazing life cycles. And maybe, just maybe, even the most nightmarish of animals can be, in its own twisted way, sort of, well … beautiful.

Have a lovely and parasite-free day.

(Disclaimer: My interest is in science education. I am not a doctor, and nothing in this article should be interpreted as medical advice. If you are here because you’re worried you might actually have rat lungworm disease, please stop browsing the Internet and talk to a real doctor. Thank you.)

Cited:

Cowie R.H. 2013. Biology, systematics, life cycle, and distribution of Angiostrongylus cantonensis, the cause of rat lungworm disease. Hawai’i Journal of Medicine & Public Health 72(6): 6-9.

Hochberg N.S., S.Y. Park, B.G. Blackburn, J.J. Sejvar, K. Gaynor, H. Chung, K. Leniek, B.L. Herwaldt, and P.V. Effler. 2007. Distribution of eosinophilic meningitis cases attributable to Angiostrongylus cantonensis, Hawaii. Emerging Infectious Diseases 13(11): 1675-1680.

Kliks M.M. and N.E. Palumbo. 1992. Eosinophilic meningitis beyond the Pacific Basin: the global dispersal of a peridomestic zoonosis caused by Angiostrongylus cantonensis, the nematode lungworm of rats. Social Science and Medicine 34(2): 199-212.

Lincoln M. 15 April 2015. Rat lungworm disease spreads fear across Hawaii Island. Hawaii News Now. Retrieved from http://www.hawaiinewsnow.com/

Lindo J.F., C. Waugh, J. Hall, C. Cunningham-Myrie, D. Ashley, M.L. Eberhard, J.J. Sullivan, H.S. Bishop, D.G. Robinson, T. Holtz, and R.D. Robinson. 2002. Enzootic Angiostrongylus cantonensis in rats and snails after an outbreak of human eosinophilic meningitis, Jamaica. Emerging Infectious Diseases 8(3): 324-326.

Lv S., Y. Zhang, P. Steinmann, and X. Zhou. 2008. Emerging angiostrongyliasis in mainland China. Emerging Infectious Diseases 14(1): 161-164.

Ramirez-Avila L., S. Slome, F.L. Schuster, S. Gavali, P.M. Schantz, J. Sejvar, and C.A. Glaser. 2009. Eosinophilic meningitis due to Angiostrongylus and Gnathostoma species. Clinical Infectious Diseases 48(3): 322-327.