Phylum Porifera and Cnideria

From sponges to Men of War

Phylum Porifera – Fact Sheet ReviewSymmetry/Body Plan: assymetrical. No digestive organs, so no “body plan”.

Digestion:Structures: collar cells, amoeboid cells

and microvilliCollar cells cause water to filter through the

sponge.Microvilli absorb microscopic nutrients.Amoeboid cells complete digestion.

Fact Sheet Review cont’dExcretion: water is let out of the osculum.

Respiration: done at the cellular level. Amoeboid cells help to circulate gases (among other nutrients).

Nervous or control system: Non-existant.

Movement: sessile (does not move; non-motile)

Fact Sheet Review cont’dReproduction: both asexual and sexual.Asexual: regeneration of cells (if the sponge

is damaged); gemmule (spore) formation; budding.

Sexual: egg and sperm cells are produced by amoeboid cells; sperm leave one sponge and are filtered into another to cause fertilization.

Representative Organisms and NotesRepresentative organism: the sponge.Classified by type of spicule in skeleton:1. Chalk sponge – skeleton is made of CaCO3

2. Glass sponge – skeleton is made of silica3. No spicules (only use soft protein fibers

called spongin).

Phylum Cnideria – Fact Sheet ReviewSymmetry/Body Plan: radial symmetry. Sac body plan (mouth = anus).

Digestion:Structures: gastrovascular cavity,

gastrodermal cellsDigestion starts in gastrovascular cavity;

nutrients eventually enter gastrodermal cells and diffuse throughout the body.

Fact Sheet Review cont’dExcretion: wastes will leave through the mouth (anus).

Respiration: done at the cellular level. Gases distributed by the gastrovascular cavity.

Nervous or control system: Simple nerve net.

Movement: motile in medusa stage. Sessile in polyp stage. Movement aided by muscle cells.

Fact Sheet Review cont’dReproduction: both asexual and sexual.Asexual: regeneration of cells (if a small

piece of the cnidarian breaks off); budding.

Sexual: egg and sperm cells are produced during the medusa stage (usually). These combine into a zygote.

Representative Organisms and NotesRepresentative organisms: jellyfish, corals, anemones, and Portugese man-of-war.Vary in how they cycle between medusa and

polyp stages.Jellyfish = mostly medusa; short polyp stage.Corals = colonial polyps (no medusa).Anemones = solitary polyps (no medusa).Portugese man-of-war = some polyps (for

feeding and floating), some medusae (for reproduction).

Representative Organisms

Notes cont’dDefenses:Cnidarians produce cnidocytes

Contain a capsule (nematocyst) that, when “tripped”, shoots out.

Traps or poisons prey.

The bitter sting…