Chapter 33

Section 2

Cnidaria and Ctenophora

Phylum Cnidaria Body Plan

• Freshwater hydra, stinging jellyfish, & flowerlike coral

• Medusa- bell-shaped

• Polyp- vase-shaped

Cnidaria- Body Plan• Epidermis- outer layer

• Gastrodermis- inner layer

• Mesoglea- between epidermis & gastrodermis

• Gastrovascular cavity- single opening or mouth

• Tentacles- flexible extensions

Cnidaria- Feeding/Defense

• Cnidocytes- specialized cells used for defense and capturing prey

• Nematocyst- cnidocyte organelle, long filament coiled up

Cnidaria- Nervous System

• Nerve net- diffuse web of interconnected nerve cells

Cnidaria Classes• Class Hydrozoa

• Portuguese man-of war

• Hydra

Cnidaria Classes• Class Cubozoa• Box jellyfish

Cnidaria Classes• Class Scyphozoa

• Jellyfish

Cnidaria Classes• Class Anthozoa

• Sea anemones & corals

Phylum Ctenophora• “Comb-like”/ Comb jellies

• Move by beating their cilia

• Have cells called colloblasts, which secrete a sticky substance that binds to their prey- located on two tentacles

Phylum Ctenophora• Sensory structure- apical organ-

ables ctenophores to sense their orientation in water

• Bioluminescence- production of light by means of a chemical reaction

REVIEW!!!• Describe how cnidarians feed.

• Name one organism from each of the 4 cnidarian classes.

• Compare and contrast cnidarians and ctenophores.