Wednesday, March 26, 2014


Before arriving in the CollinLab I´d never worked with porcelain crabs (porcellanids).  This is my first time with these small crabs.

They are quite different from the crabs you see on your dinner plate. Their bodies are compact and flattened; this is an adaptation for living and hiding under rocks. They are very abundant along the Pacific Coast where they congregate in tide pools under rocks because they are very sensitive to desiccation.

Another characteristic of porcelain crabs is that the antennae are inserted external to the eyes, not between the eyes like in other crab families.
Petrolisthes tridentatus

Porcelain crabs are quite fragile animals.  They often shed their limbs to escape predators (or me), hence their name. They are pretty fast and when you have to collect them, you should be very carefully because you can end up catching only the body… The good news is that they only need a few days to regenerate the legs they lost.
P. armatus without a cheliped…yes, I tried to collect it.. 

I´m working with one species of these Porcellanids, Petrolishtes armatus.  They can be distinguished from similar species by an orange spot on the chela and blue mouthparts. Also another unique characteristic useful to differentiate them from another Petrolisthes species, P. tridentatus, is that the cheliped has 3 spines that are very clear to see.

P. armatus and P. tridentatus, very difficult to differentiate in the nature. 

But under the microscope you can see the difference in the cheliped

A few months ago I had no idea what they are.  And now…they are my workmates and I have to admit that they are amazing!

Thursday, March 20, 2014

Don't Wake the Octopus

Animals in the intertidal zone make up a complex community. Many animals live together in small spaces. Under one rock, you might find several different snails, worms, crabs, sponges, and anemones living side-by-side.

However, sometimes animals must compete for the best living spaces. Some need protection from the water, sunlight, and predators who eat them. Biologist Patrick Green got a "first-hand" (pun intended) experience of this not-so-neighborly competition when he went looking for a resident. Mantis shrimp live in holes in the rocks. Instead of finding a shrimp in one burrough, he found an octopus! This video shows what happened when he startled it!

by Nina Dropcho