Exercise 36

Question 1

What are the three common characteristics of all animals?

Answer 1

Eukaryotic
Multicellular
Ingestive feeding heterotrophs

Question 2

Which phylum is radially symmetric? Asymmetric?

Answer 2

Cnidaria [jellyfish, hydra], Porifera [sponges]

Question 3

T/F: Cnidarians have true tissues and organs, but poriferans do not.

Answer 3

F. Cnidarians do not really have organs, but they do have tissue.

Question 4

What does sessile mean, and who is sessile?

Answer 4

Attached, not motile. All poriferans, some cnidarians, especially polyps stages.

Question 5

Poriferans feed by _______. Most cnidarians feed by _________.

Answer 5

Filter feeding [intracellular digestion], extracellular digestion and intracellular digestion.

Question 6

What do choanocytes do? What do amoebocytes do? What phylum are they part of?

Answer 6

Draw water in and filter food; many things, they are motile, can digest, and differentiate; Porifera

Question 7

What is a spicule? A spongocoel?

Answer 7

A crystallin structure that looks like a ninja star. Spongocoel is the large internal cavity in a Grantia.

Question 8

Name all members of Porifera.

Answer 8

Grantia, Spongia, Euplectella

Question 9

What is an ostium cell? An osculum?

Answer 9

A cell that helps bring water through to choanocytes. The big open top of a Grantia.

Question 10

What are spicules made of in

• Grantia
• Euplectella
• Spongia

Answer 10

• crystalline
• silicon
• spongin protein (makes up the flexible skeleton)

Question 11

Most sponges produce both female and male ______. They can reproduce both _____ and _____.

Answer 11

gametes, sexually, asexually

Question 12

How many germ layers do Cnidarians have? Worms? What are the names of the layers in cnidarians?

Answer 12

2. 3. Endoderm and ectoderm.

Question 13

Cnidarians don’t have a mesoderm, but they do have a gelatinous _______.

Answer 13

mesoglea

Question 14

What is polymorphism? Who does it? What morphs does it specialize in?

Answer 14

Having more than one form. Cnidarians. Polyp and medusa.

Question 15

In cnidarians, ______ hold stinging harpoon structures called _______.

Answer 15

cnidocytes, nematocysts

Question 16

What is the name for an immature polyp?

Answer 16

A planular larva, or planula.

Question 17

Name the three Cnidarian classes and tell why they are different.

Answer 17

Hydrozoa: dominant polyp
Scyphozoa: dominant medusa
Anthozoa: only polyp

Question 18

What are the three species of class Hydrozoa?

Answer 18

Hydra: polyp only, attach to surfaces with basal disk (sometimes even water surface)
Obelia: Colony polyps, but free swimming medusa. Food polyp: gastrozooid [has flagella to catch food], reproduction polyp: gonozooid.
Physalia: Portuguese man of war, strong nematocysts but no cnidocytes, looks like a medusa, but actually is a colony of polymorphic polyps.

Question 19

What is the species in class Scyphozoa?

Answer 19

Aurelia. Dominant medusa. DOES have cnidocytes. Polyp stage is called a scyphistoma.
Planula looks like a fingerprint
Scyphistoma looks like a torch on fire (tentacles)
Ephyra looks like a flower that isn’t yet mature.
Medusa looks really white and elegant.

Question 20

What two species are in class Anthozoa?

Answer 20

Metridium: Sea anemone. No medusa. Reproduce by fragmentation of basal disk.
Tubipora: Coral. No medusa. Contains iron salts for color. The whole coral is made of calcium carbonate.

Question 21

What direction do flagellated canals face? What about incurrent canals?

Answer 21

Inside towards spongocoel. Outside.