Chapter 33 Introduction to Invertebrates

Question 1

Animals in this phylum are informally called sponges.

Sponges are sessile animals that lack tissues. They live as filter feeders, trapping particles that pass through the internal channels of their body. (5,500 species)

Answer 1

Porifera

Question 2

Radially Symmetrical, Diploblastic animals with a gastrovascular cavity

Corals, jellies, and hydras belong to this phylum

Answer 2

Cnidaria

Question 3

Includes flatworms with a simple nervous system and saclike gut

Answer 3

Acoela

Question 4

Trichoplax adhaerens is the only species
Composed of a bilayer of a few thousand cells
They reproduce by dividing into two or budding off many multicellular individuals

Answer 4

Placozoa

Question 5

(comb jellies) are diploblastic, radially symmetrical animals
They have eight “combs” of cilia that propel them through the water
Comb jellies compose much of the ocean’s plankton

Answer 5

Ctenophora

Question 6

hairy bellies; most species live on the bottoms of lakes or oceans, where they feed on small organisms and partially decayed organic matter.

Answer 6

Gastrotricha

Question 12

live as sessile colonies and are covered by a tough exoskeleton

Answer 12

ectoprocta

Question 13

lamp shells; may be easily mistaken for clams or other molluscs. however most have a unique stalk that anchors them to their substrate as well as a crown of cilia called a lophophore

Answer 13

brachiopoda

Question 14

has one species only; was discovered in 1995 on the mouthparts of a lobster. this tiny creature has a unique body plan and a bizarre life cycle: males impregnate females that are still developing in their mothers bodies. the fertilized females escape, settle elsewhere on the lobster, and release their offspring

Answer 14

cycliophora

Question 15

ribbon worms; swim through water or burrow in sand, extending a unique proboscis to capture prey; have a reduced coelom, so their bodies are relatively solid. they also have an alimentary canal and a closed circulatory system in which the blood is contained in vessels and hence is distinct from fluid in the body cavity

Answer 15

nemertea

Question 16

segmented worms, distinguished by their body segmentation. earthworms are the most familiar of this phylum but most like in marine or freshwater habitats

Answer 16

annelida