Horseshoe crabs now considered arachnids

[Justin H]

New research has been published to establish that horseshoe crabs (xiphosura) rightfully belong to the class Arachnida. Here's an excerpt:

"Our analyses support the inference that horseshoe crabs represent a group of aquatic arachnids, comparable to aquatic mites, breaking a long-standing paradigm in chelicerate evolution and altering previous interpretations of the ancestral transition to the terrestrial habitat."
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Google pictures of them. They look like isopods from the top but on the bottom are 8 legs, pedipalps, and spider-like chelicerae. Really makes you think about the Earth's transition from aquatic organisms to terrestrial... trippy stuff!

 

[Schledog]

I knew they were arthropods but I didn't know this. Very cool.

 

[dmac]

My girlfriend just sent this to me. Haven't read more than the abstract, but sounds pretty cool!

 

[dord]

Neat! I've wanted to keep horseshoe crabs, but they require specialized marine aquariums with very deep, fine sand beds. It's a shame young L. polyphemus are sold as sand-stirrers for reef aquariums where they die within months due to starvation and too warm water. C. rotundicauda would likely be more suitable for captivity due to their size.

 

[Villagecreep]

Fascinating!

 

[The Snark]

It's a shame young L. polyphemus are sold as sand-stirrers for reef aquariums where they die within months due to starvation and too warm water.

A common theme in keeping these animals, whether for public display, scientific research, or breeding. A researcher at Telonicher marine labs put it succinctly: "if it isn't growing, it's dying."
Water temperature is a very critical factor. Ask any crab fisherperson. Warm water=bad year. No growth. Shells don't fill in. Trout give a perfect example: only 2 degrees F difference between growing and simply burning food. Dungeness crabs, 3-5 degrees.

 

[Margot J]

Very cool! Thanks for sharing!

 

[FrDoc]

Oh great, here we go. "Why is my horseshoe crab not eating? Is it okay to handle my horseshoe crab? Are there any blue horseshoe crabs? Do you name your horseshoe crabs?"

 

[velvetundergrowth]

Neat! I've wanted to keep horseshoe crabs, but they require specialized marine aquariums with very deep, fine sand beds. It's a shame young L. polyphemus are sold as sand-stirrers for reef aquariums where they die within months due to starvation and too warm water. C. rotundicauda would likely be more suitable for captivity due to their size.

I kept the Asian Mangrove species in my 150g Brackish tank a long while ago, the little guy/girl lived happily and grew some for over 2 years alongside a Green Spotted Puffer and a couple of Monodactylus. They can handle a very low specific gravity, there are reports of them being found in fully freshwater locations.
They do not grow nearly as large as their marine counterparts (which are almost impossible to house correctly outside of public aquaria) and seem relatively content in large, open-bottom tanks.

I'm getting back into the hobby after a long "break" and these are one of the species I'm considering keeping again. The main issue is obtaining legitimate C. rotundicauda and not just small Limulus species.