Phylum Cnidaria

Question 1

Phylum Cnidaria

Answer 1

A diverse array of sessile and motile forms that include jellyfish, sea anemones, and corals

Have simple radially symmetrical diploblastic body plan

Question 2

Phylum Cnidaria Body Plan

Answer 2

Sac-like w/ central gastrovascular cavity

Single opening to gastrovascular cavity (both a mouth and anus)

Tentacles equipped with stinging cells

Outer epidermis derived from ectoderm and gastrodermis derived from endoderm

Gas exchange via diffusion across epidermis

Question 3

Define cnidocytes

Answer 3

Stinging cells that surround the opening of tentacles for prey capture and defense

Question 4

Variation in Cnidaria Body Plan

Answer 4

Two variations.

1. Sessile polyp which attaches to the substrate oral end upwards (sea anemone)
2. Bell-shaped, motile medusa that moves freely through water via a hydrostatic skeleton, oral end downwards (jellyfish)

Question 5

How do Cnidaria feed?

Answer 5

Predators that use tentacles to capture prey

Question 6

Nematocysts

Answer 6

Complex organelles in Cnidaria that deliver stinging toxins to immobilize prey

Question 7

Major Clades of Cnidaria

Answer 7

Medusozoa (have a medusa stage) and Anthozoa (polyps)

Question 8

Two Groups of Clade Medusoza

Answer 8

Hydrozoans and Scyphozoans/cubozoans

Question 9

Hydrozoans

Answer 9

Group in Clade Medusoza that alternate between polyp and medusa forms

The polyp is sessile, colonial, and reproduce asexually.

The Medusae produce asexually with budding but also produce sexually. Their motile larvae settle to transform into polyps

Question 10

Clade Anthozoa

Answer 10

Clade of Cnidaria that includes coals and sea anemones.

They only occue as polyps w/out a medusa stage.

Some live alone, others are colonial (like coral with a symbiotic relationship with algae)