Cnidarians & Porifera Study Guide

Lab Quiz study guide: Cnidaria, Porifera

Animals are characterized as eukaryotic, multicellular, and ingestive-feeding heterotrophs.

Porifera (Sponges)

Simplest multicellular animals, No true tissues or organs, Body full of pores (ostia) and canals

Structure & Function:

Asymmetrical (most lack body symmetry), Cells are loosely organized

Specialized cells:

• Choanocytes (collar cells): create water flow & capture food 

• Amoebocytes: distribute nutrients

Feeding:

Filter feeders (water flows in → food trapped by microvilli→ water exits through osculum)

Skeleton:

Made of spicules (silica or calcium) or spongin fibers (proteins)

Reproduction:

Asexual (budding, regeneration) and sexual

Many are hermaphrodites (posses both male and female reproductive organs, gametes)

Habitat:

Mostly marine, some freshwater

Cnidaria (Jellyfish, corals, sea anemones)

More complex than sponges, Have true tissues, Radial symmetry (body arranged around a central axis)

Structure & Function:

Two tissue layers:

• Epidermis (outer)

• Gastrodermis/endodermis (inner)

Gel-like layer in between called mesoglea

Body forms:

     Polyp (sessile, e.g., corals)

     Medusa (free-swimming, e.g., jellyfish)

Unique Feature:

     Cnidocytes (stinging cells) with nematocysts for capturing prey and defense

Carnivorous (capture prey with tentacles)

Nervous System: Simple nerve net (no brain)

Reproduction:

• Both sexual and asexual

• Some alternate between polyp and medusa stages

Habitat:

• Aquatic, mostly marine