Question

The first triploblastic animal phylum is Phylum ____________.

		Mollusca
		Nematoda
		Rotifera
		Platyhelminthes

The nontaxonomic term sea slug encompasses a wide variety of marine gastropods. One feature they share as adults is the lack of a shell. We might think, therefore, that they represent defenseless morsels for predators. In fact, sea slugs have multiple defenses. Some sea slugs prey on sponges and concentrate sponge toxins in their tissues. Others feed on cnidarians, digesting everything except the nematocysts, which they then transfer to their own skins. Whereas the most brightly colored sea slugs are often highly toxic, others are nontoxic and mimic the coloration of the toxic species. Their colors are mostly derived from pigments in their prey. There are also sea slugs that use their coloration to blend into their environments.

		nematocysts
		B. an incurrent siphon
		a radula
		a mantle cavity

natural predator of the crown-of-thorns sea star is a mollusc called the Giant Triton, Charonia tritonis. If the triton uses a radula to saw into the sea star, which Class of Mollusca would you think the triton belongs to?

		Gastropoda
		Bivalvia
		Polyplacophora
		Cephalopoda

Which of the following in NOT unique to Phylum Mollusca?

		radula
		chromatophores
		coelom
		mantle

What would be the best anatomical feature to look for to distinguish a gastropod from a chiton?

		presence of muscular foot
		presence of a radula
		production of eggs
		number of shell plates

1. An animal cannot be acoelomate if it is also triploblastic.
   1. True
   2. False

During typical earthworm reproduction ________________.

		the individual self-fertilizes
		B/. monecious individuals exchange sperm
		fertilization occurs during copulation between males and females
		reproduction is by parthenogenesis

Class Cephalopoda is unique among the classes in Phylum Mollusca in that ____________________________

		they undergo direct development
		they have an open circulatory system
		they have a closed circulatory system
		Both A and C

While sampling marine plankton in a lab, a student finds a large number of fertilized eggs. The student raises some of the eggs in the laboratory for further study and finds that the blastopore becomes the mouth. The embryo develops into a trochophore larva and eventually has a true coelom. These eggs probably belong to a(n).

		gastropod
		nematode
		platyhelminthes
		could be either a gastropod or a nematode

Answer 1

• D) platyhelminthes

platyhelminthes commonly called flatworms and their bodies are flattened dorsoventrally with three germ layer

• C) radula
• A) gastropods
• B) chromatophores

common characteristics are

triploblastic coelomates

forms mantle cavity

having radula

• D) number of shell plates
• A) false

acolelomates have a triploblastic body plan forming three primary embryonic cell layers

• C) fertilization occurs during copulation between males and females

they are having hermaphroditic individuals

• D) both A and C
• A) gastropods

these eggs belong to phylum mollusca