Song of the Shrimp

New visitors from the Scientific American article: Welcome! I hope you find some things that interest you here. My forum is starting to pick up, and I would love to see some new blood there. Bryan, who I met at the Green Futures expo, I hope you can forgive me for not writing about the animal you suggested, but I completely forgot. For two months. Sorry.

Image from Ann Dickinson

This is the California Freshwater Shrimp (Syncaris pacifica). It doesn't look like much, which is actually a anti-predatory device, as its translucency helps hide it from predators. If hiding doesn't work, it has a protective spine useful for jabbing into a predatory fish's mouth.

These shrimp are only found in a few counties in the Bay Area in California, and seem to be fairly picky about their habitat. They live in the runs¹ of streams that have undercut banks, exposed roots, and overhanging vegetation. All of these features provide the Freshwater Shrimp with numerous hiding places.

The problem comes when those hiding places are disturbed. There are quite a few ways this can happen, all of which have the final result of removing the vegetation that these shrimp call home. The trees that provide the overhanging roots are removed when a stream is channelized, and agriculture and livestock fill the stream with runoff that buries those roots in silt.

There is quite a bit of good news going for the California Freshwater Shrimp. For one thing, its numbers appear to have almost quadrupled between 1991 and 2000. Another thing is that a number of teachers and students are using this as their rallying species to help teach people about freshwater habitat, and saving some endangered species in the process. If anyone in those programs reads this: I salute you. You will be able to tell future generations that you helped save a living thing from extinction.

¹Runs are the areas in streams halfway between the shallow, fast moving riffles, and the slow, deep pools. This site explains these quite well.

Put the Lime in the Coconut

Oversized arthropods will always be welcome on this blog. Alright, most arthropods are condidered icky enough, but there is a special type of revulsion saved for really big creepy-crawlies. Well, I've already written about the largest freshwater invertebrate, so the largest terrestrial invertebrate can't be far behind¹. Also hailing from order Decapoda, this is the Coconut Crab (Birgus latro).

Image from Cook Islands Natural Heritage Trust³

When I say "big," I'm sure that you're looking for some measurements to back that up. The Coconut Crab, also known as the Robber Crab or Palm Thief, has a body length of 1½ feet, with a legspan of 3 feet. It weighs up to 9 pounds but its strong claws can apparently lift up to about 60 pounds. Yes, this crab can lift a medium-sized dog.

Why is it so beefy? Well, anyone who has tried to open a coconut with simple tools can answer that. This is not an easy fruit to get into. The Crab will strip the outer husk near the germination pores (those things that make a coconut look like a bowling ball). It will then use one of its legs to punch a hole through the inner husk, and break the coconut apart. Once again, ARKive provides us with wonderful footage of this in action.

Mating occurs quickly and on land, and the female carries the eggs under her abdomen. She then drops those into the ocean, where they hatch into marine larvae that look something like shrimp. Coconut Crabs are closely related to the Terrestrial Hermit Crabs you'd see in pet stores, and the young will find snail shells to protect their soft rear-end. As they grow larger, their abdomen grows a thick carapace, so they lose the need to find snails. Good thing, too, considering their size. They also become fully terrestrial, though they can still drink seawater.

Coconut Crabs are found dispersed throughout islands in the South Pacific. Being a huge crab, no one would be surprised that they're hunted for food. Being an island species also means invasive species like rats, pigs, and ants are a problem for the juveniles. As the islands get more populated, habitat destruction is a problem as people encroach on the beaches. As population estimates vary from island to island depending on the number of people there, the IUCN lists the Coconut Crab as Data Deficient.

Conservation varies from island to island as well. Some places set hunting limits, while others have set up breeding programs. More research needs to be done to really find out how to help these huge creepy-crawlies out.


¹The fact that weight is pretty much meaningless in the ocean leads to some pretty big invertebrates down there. The Japanese Spider Crab²(Macrocheira kaempferi) with a 13 foot legspan wins as the largest arthropod, while the Colossal Squid (Mesonychoteuthis hamiltoni) puts all other invertebrates to shame with a body length of 33 feet.
²You can't tell me that picture doesn't look like a video game boss.
³The image that many of you were expecting to see was probably this one, which I would have used if I could have found an original source.

Meet Ya Down at the Crawdad Hole

I’ve got some exciting news that isn’t immediately related to the EUT of the week, but is still pretty cool. I got cited by Wikipedia! And, even more exciting, EDGE just put up a new Amphibians chapter… and I got cited by them! For the same post! Looking at my Sagalla Caecilian post, it’s not even particularly in-depth, but it’s somehow linkable by pretty big names. Excuse me while I go deflate my ego….

I found this week’s EUT a while ago, but somehow never got around to writing about it. Like a few other of my past posts, if you take a perfectly innocuous animal and make it huge, it slips right into the ugly category. On a side note, I’m surprised how few crustaceans I’ve written about so far.

Image from RamPumps.com

The Tasmanian Giant Freshwater Crayfish (Astacopsis gouldi) has enough modifiers in its common name that I don’t particularly need to explain its range, its habitat, or its superfamily. Its size could use some description, as it isn’t Giant Salamander or Giant Catfish giant, with a record of six and a half pounds and two and a half feet, it’s still a freakin’ big crayfish, not to mention the largest freshwater invertebrate.

I suppose I could also define its habitat more precisely, as they prefer clean, wooded rivers, and the juveniles are mostly found in headwater streams. Like most crayfish¹, the Giant Crayfish is omnivorous, or, as this site states: “Their diet consists mainly of decaying wood, but they will also consume leaves, small fish, and rotting flesh.”

As a general rule, as a species gets larger, it takes longer to reach sexual maturity, and this is no exception. It takes males nine years and females fourteen years before they’re able to make little Giant Crayfish, and they can live up to 40 years. This, coupled with the completely unsurprising problem of overharvesting, has lead to their decline in numbers, and subsequent listing. The problem of habitat loss exists for the Giant Crayfish, just like it shows up for most headwater species.

Tasmania is doing commendably well in terms of conservation efforts. It has been illegal to collect a Giant Crayfish since 1995, and there have been habitat conservation programs and education programs running around the island in an attempt to save these cute little massive crayfish.

¹I know, I know, not a fish. A lot of the Australian sources are calling it a lobster, and I suppose I could always resort to “crawdad,” but I’ve always called them crayfish, and never thought of them as fish.

"Will You Walk Into My Parlor?"

Sorry for such a late post. I don’t have any good excuses; I’ve just been slacking. A few weeks ago, Greg (who also suggested the Siaga Antelope) suggested an EUT for me¹. I found out that its story is unavoidably attached to another Endangered Ugly Thing.

Image from Fish and Wildlife Service

This is the suggested animal, the Kauai Cave Amphipod (Spelaeorchestia koloana). It’s a blind, terrestrial, shrimp-like crustacean that inhabits the small caves formed by gas escaping through the Hawaiian lava². It lives happily on the detritus to be found in those caves. The Kauai Cave Wolf Spider (Adelocosa anops) inhabits the same habitat, except it lives happily on the Cave Amphipods to be found there. They’re only found in about five different locations on the island of Kauai, most of which are on private property.

Everyone seems to find it strange that the government would protect both a predator and its main prey item. Someone even did a cartoon on it, and, quite frankly, I don’t often see people trying to anthropomorphize blind amphipods. Or amphipods of any kind.

Look, it’s not that strange. The Kauai Cave Amphipod is not endangered because the Kauai Cave Wolf Spider eats it. The amphipod has had millions of years to evolve defenses against the spider. They’re both endangered because of Hawaii’s³ rapid development. Y’know, paving over the lava, agriculture, and heavy use of insecticides for invasive species control (and other less noble goals). Protection is just starting, as they only got added to the list in 2003, though they’ve been working on restoring the caves since 1995.

¹Please, please, please keep sending in those suggestions. It makes life so much easier for me.
²Yes, I know I just wrote about a Hawaiian EUT. See above footnote.
³I’m trying to decide if “Hawai’i’s” would look weird. Yeah it does.

I Wish They All Could be California Arthropods

This one falls into the category of ugly things that I came across while randomly looking through The List. I'm going to keep on the lookout for any others, but I'm running low on EUTs that I've heard of. If anyone has any suggestions, start sending 'em in.

Image by Aviva Rossi

Looking somewhat like a cross between a horseshoe crab and a shield bug, the vernal pool tadpole shrimp (Lepidurus packardi) gets the distinction of being the first invertebrate on Endangered Ugly Things. It will not be the last, as the diversity of invertebrates is staggering, and, with the exception of butterflies, they're pretty much all considered ugly.

Distantly related to triops and sea monkeys (actually brine shrimp), which you can buy at any decent science shop, the tadpole shrimp share their ability to breathe through their 35 or so phyllopoda (leaf-feet) which also act as paddles. They grow up to a whopping 2 inches in length, eat organic matter smaller than them, and get eaten by everything that normally eats benthic macroinvertebrates: other invertebrates, amphibians, fish, and some birds.

The vernal pool tadpole shrimp hangs its small, strangely shaped hat in ephemeral pools in the San Fransisco bay area that dry out every summer. It survives these dry spells by laying drought-resistant eggs, which will hatch once the pools fill up again.

There are no big surprises with why these are endangered. Habitat destruction is always a problem when your habitat is a big wet spot, and someone says, "Hey, this looks like the perfect place for a shopping mall." Suddenly, your big wet spot is under a ton and a half of concrete. Agricultural and urban runoff, overgrazing, and invasive plants are also having an effect on the tadpole shrimp. Hope exists for them in the form of programs to save wetlands, which are being put into effect all over the United States.