Invertebrates, Cnidarians, Molluscs: Key Concepts and Body Structures

Which group of Cnidarians includes box jellies and Irukandji?

Cubazoans

What are the two primary body forms found in Cnidarians?

Polyp and Medusa

What are the stinging cells and the capsules containing the barbs called in Cnidarians?

Cnidocytes and nematocysts

Is a Portuguese man o' war a true jellyfish (scyphozoan)?

No, it is a hydra (a colony of polyps)

What are two key differences between Ctenephores and Cnidarians?

Ctenephores use colloblasts instead of nematocysts and possess a complete gut system

What is the function of a colloblast?

A sticky cell used by Ctenephores to capture prey

What does the word 'Mollusc' mean?

Soft body

What are the four main classes of molluscs?

Chiton, Bivalve, Gastropods, and Cephalopods

What is torsion in gastropods?

The twisting of the digestive system and mantle cavity to accommodate a shell

What are the skin cells that allow cephalopods to change color?

Chromatophores

Which group of gastropods lacks a shell?

Nudibranchs

Which class of molluscs is the largest?

Gastropods

In which group of molluscs are the head and radula absent?

Bivalves

How do nudibranchs protect themselves without a shell?

They are often toxic and some can reuse nematocysts from their prey

What is the collective term for animals without a backbone?

Invertebrates

Which class of Cnidarians is a free-swimming medusa for most of its life?

Scyphozoans

What is the function of the mantle in molluscs?

It secretes the shell and handles waste disposal, sensory reception, and respiration

What is the unique, tongue-like feeding tool found in most molluscs?

Radula

What is the oldest part of a bivalve shell called?

Umbo

What is the basic body plan of a mollusc?

A head, a muscular foot, and a visceral mass

What are the defining characteristics of a chiton?

A dorsal shell made of 8 plates, a ventral muscular foot, and a ventral mouth with a radula

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