Crustacean Echinoderm Molluscs Observations

Today students observed specimens of some of the organisms we have been discussing in class. Many students were surprised that these "specimens" were purchased at the grocery store and that some of them like the squid could be eaten. Perhaps I forgot to mention calamari?

For molluscs, students observed a mussel, clam, oyster, and squid. Students looked in the inside of the bivalves and some questioned why anyone would eat them. I think they were more surprised by how empty the shell actually was. The squid was a hit! Students were able to observe its siphon, the beak, feel the pen (the inner supportive shell), and see all the tentacled arms, plus it was leaking a little bit of ink. Dale, Nick, and Rachael had some excellent squid drawings.

Students observed horseshoe crabs and put together a miniature model. Students observed crustaceans like blue crabs, snow crabs, a lobster and shrimp that still had their heads.
Maria C (with a C) is impressed with the shrimp. Shrimp with heads are not easy to find because we queasy Americans often do not want to eat things that appear to be staring at us. Shrimp with heads have their legs too - those things that are on the tail that you are used to peeling off are actually swimmerets.

On the lobster, students had to identify the two claws - the shredder and the crusher. Students also looked the mouth and decided whether they thought a lobster had teeth. Brittany S, Luke, Kaythurn, and Raven get a closer look at the lobster and its claws.

Students compared two crabs - the blue crab and the snow crab. On the blue crab, they correctly identified it was a male and then took a look at the three types of legs. Crustaceans have ten legs, but on the blue crab the first pair are pincers, the next three pairs are walking legs, and the fifth pair of legs actually has a fin because the blue crab can swim. Snow crabs are a kind of spider crab and have a bumpy skin to encourage the growth of algae for camouflage. Alicia is checking out the blue crab - she checked out everything in this activity.

Students looked at the tests (endoskeletons) of sea stars, sea urchins, a sand dollar, and a sea biscuit. The hole or opening on the bottom in the middle is the mouth of the echinoderm. Sea urchin tests are bumpy from where the spines used to be attached.