Sunday, October 29, 2006

Yellow Arachnids of Texas

Take a look at the U.S. Endangered species list, arachnid section. Out of twelve arachnids, eleven of them fall into the form of “X Cave Y,” where X is the name of a cave, and Y is the type of arachnid. Ten of these are from two counties in Texas. Since these aren’t discussed in depth separately, we’ll talk about the whole bunch. They are, in no particular order, the Bee Creek Cave Harvestman (Texella reddelli), the Bone Cave Harvestman (Texella reyesi), Robber Baron Cave Harvestman (Texella cokendolpheri), the Braken Bat Cave Meshweaver (Cicurina venii), the Government Canyon Bat Cave Meshweaver (Cicurina vespera), the Madla's Cave Meshweaver (Cicurina madla), the Robber Baron Cave Meshweaver, (Cicurina baronia), the Tooth Cave Pseudoscorpion (Tartarocreagris texana), the Government Canyon Bat Cave Spider (Neoleptoneta microps), and the Tooth Cave Spider (Leptoneta myopica). For your viewing pleasure today, we have the Bone Cave Harvestman, simply because it has a cool name (and if any Metalheads reading this are at a loss for a band or album name, you’re welcome).

Image from City of Austin
Image from City of Austin

Each of the arachnids is predatory, feeding on smaller cave-dwelling invertebrates. They are eyeless, and paler than its superterranian counterpart, often becoming orangish or yellowish. Otherwise, the spiders (meshweavers included) are similar to the everyday house spiders, and the same goes with the harvestmen, though I had to look them up to find that harvestman was another name for daddy longlegs. Pseudoscorpions, which I’m not sure how many people are familiar with them (I’m not), look much like, well, scorpions, just tailless, with small venom glands in their claws.

What is this cave habitat that contains all these endangered species, and why are there so many endangered arachnids in such a small area (relatively, we’re talking about Texas here)? The Texas karst is a limestone area that, due to the erosion of softer rocks, has formed extensive cave systems. Since they have formed (and continue to do so, they won’t stop for us) by water flow, anything dumped on the surface goes right through to all of those places where eyes are luxury items. While pollution is certainly a problem, the major issue is development encroachment, which has the possibility of destroying the area around caves or the caves themselves, or changing the temperature of the cave, which has been constant since, oh, the last ice age. Invasive plants can bring in red fire ants, which compete with the arachnids for food and sometimes prey on them.

There’s another reason for the density of endangered cave arachnids: the density of spelunking entomologists. Like it or not, much of the information about endangered species comes from a few people looking for specific species. Since they know exactly what they’re looking for, they can determine that these species are endangered, and go through the rigmarole of getting them listed. There are tons of endangered species running all over the place, but since no one’s described them, or looked closely enough at them, they go unnoticed.

Sunday, October 22, 2006

Oh, Caecilian, You're Breaking my Heart

Within amphibians, there are the frogs and toads (order Anura; it means tailless), which can be considered too cute to include on this blog and there are the salamanders and newts (order Caudata or Urodela, both meaning with a tail), which I’ve already posted about one1. There is a third order of amphibians, of which most people have not heardof. The scientific name for the order is either Gymnophiona (naked snake) or Apoda (footless), both of which are stunning endorsements for the inclusion of a caecilian on this blog.

Image from ARKive
Image by John Measey

The Sagala Caecilian (Boulengerula niedeni) is a species that was first described in 2005. Its name comes from the hill it inhabits (Sagala Hill in southern Kenya). Since they’re such a newly discovered species, there’s a lot that still isn’t known about them, but scientists are pretty sure that their range is about 30 sq. km, which is smaller than Manhattan Island. Right there, with that small of a range, they become listed as Critically Endangered. Along with its already minimal range, large-scale farming disrupts streamside habitats, where they make their home, and introduces pollutants.

I’m having problems finding specifics about the Sagala caecilian, such as what it eats (probably small invertebrates) and specific reproductive history, though caecilians are the only order of amphibians that perform internal fertilization. In fact, the discerning feature of this amphibian, used to describe it as a new species, is its oddly shaped phallus.

On a different note, I have received my Official EUTshirt, and I am pleased with the quality. The concept of a cute lamprey stuck with me since I wrote about it. I asked friends and family if the idea of a line of cute Endangered Ugly Things t-shirts went against everything EUT stood for, and they said, “Maybe.” Well, they’re up and buyable anyway. Enjoy, and I’m up for any suggestions of other EUTs, since I’m having slight problems finding good ones.

1Possibly more to come, ‘cause if you thought the hellbender was big and ugly, there are some bigger, uglier ones out there.

Saturday, October 14, 2006

I Only Have Ears For You

I promised myself I wouldn’t post a mammal unless it was certainly ugly. I have come to the realization that, y’know, I’m a pretty bad judge of ugly. Bats with noses like satellite dishes are just par for the course. So, here’s a bat with ears about half as long as its entire body and facial glands on either side of its nose.

Image from Bat Conservation International
Image from Bat Conservation International

Those glands on the Virginia Big-Eared Bat (Corynorhinus townsendii virginianus) probably emit pheromones. Nothing quite like natural perfume sacs right next to your nose (it’s amazingly difficult to definitely determine this sort of thing). Like many other bats, they are nocturnal insectivores, feeding mostly on moths. Unlike most bats, they’re late sleepers1, as they leave the cave about an hour after dark instead of an hour before. Since they fly fairly slowly, they’ve got their share of predators, including barn owls, and the less native feral housecat.

Big-eared bats mate in the fall and early winter. Since bats in temperate habitats tend to hibernate all winter, this might not seem like a good idea. But fear not, dear reader, for the female big-ear has a trick up her… sleeve. She is able to keep the sperm through the winter, ovulate in the spring, and have the baby (well, pup, actually) in early summer, when all the juiciest moths are out and getting in people’s campsites.

Not only are the big-ears late sleepers, they're also light sleepers in the winter. When the bats are hibernating, disturbances cause them to wake up, shift around, and lose valuable energy for managing their way through the winter2. Thus, spelunking and other caving activities are potentially dangerous to these bats. Intrusions during other times of the year can directly affect young, or drive the bats to look for a new home.

To keep these occurrences at a minimum, gates or fences have been placed around the colonies by concerned government employees. Studies on big-ears’ favorite roosting places are being conducted to see what else we can do to study them. And, on the political front, in 2005, the Virginia Big-Eared Bat was chosen to honorably represent the Commonwealth of Virginia as the Official State Bat.

1Like many college students.
2Also like many college students.

Sunday, October 08, 2006

Lady Madonna - The Beatles

As beetles go, the American Burying Beetle (Nicrophorus americanus) isn’t terribly ugly (this may be due to its nice black and reddish orange pattern on its back). It is a little big (about an inch). On the other hand, invertebrates need a bit more screen time on this blog, and when you’re competing with pandas and tigers, anything with more than twice as many legs as eyes fits into the ugly category.
Image from University of Nebraska State Museum
Image from University of Nebraska State Museum
There’s another thing going for this nocturnal beetle’s inclusion here. People really don’t like carrion eaters, despite their impressive ability to smell a dead body from two miles away within an hour of death. Of course, their habit for eating dead things is helpful for returning nutrients to the soil, and they even have orange mites living on them, which keep the beetle and the carcasses free of many microbes and fly eggs (nothing like a clean corpse).

The impressive part about this beetle is its childcare policy. While most insects tend to drop their eggs and either leave or die, burying beetles are almost… vertebrate in their parental care. After one finds a suitable dead thing, a dove or chipmunk, for example, it will send out a huge amount of pheromones into the air. When a potential mate shows up, the two work together to move the carcass to an acceptable location, and, once there, live up to their name. Once the body is under a few inches of soil, they strip off the skin and some appendages, and generally form the body into a flesh ball, applying excretions that stop fungal growth. The pair then mate, lay 10 to 30 eggs in an adjacent tunnel, and wait for them to hatch. Once the larvae have hatched, the adults will help them out by regurgitation feeding, a la birds, or by moving the young to particularly choice pieces of carcass.

The American burying beetle has a cause for endangerment I haven’t talked about yet: habitat fragmentation, which reduces available prey items, and increases competing scavengers, like raccoons and crows. It also separates the populations, resulting in minimized gene flow. Pesticides and light pollution (remember, they’re nocturnal) don’t help, so now the beetle exists only in isolated pockets, a shadow of its former range.

One does not normally think of breeding programs and reintroduction of insects, but they exist for the burrowing beetle. More than 200 beetles have been reintroduced into Southern Ohio since 1998, and Massachusetts has had a head-start program to bolster their burying beetle population since 1994. Many other states are doing their part to help bring this little necrophage back from the brink.