From sponges to Men of War

Phylum Porifera – Fact Sheet Review Symmetry/Body Plan: assymetrical. No digestive organs, so no “body plan”. Digestion: Structures: collar cells, amoeboid cells and microvilli Collar cells cause water to filter through the sponge. Microvilli absorb microscopic nutrients. Amoeboid cells complete digestion.

Fact Sheet Review cont’d Excretion: 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’d Reproduction: 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 Notes Representative organism: the sponge. Classified by type of spicule in skeleton: 1. Chalk sponge – skeleton is made of CaCO 3 2. Glass sponge – skeleton is made of silica 3. No spicules (only use soft protein fibers called spongin).

Phylum Cnideria – Fact Sheet Review Symmetry/Body Plan: radial symmetry. Sac body plan (mouth = anus). Digestion: Structures: gastrovascular cavity, gastrodermal cells Digestion starts in gastrovascular cavity; nutrients eventually enter gastrodermal cells and diffuse throughout the body.

Fact Sheet Review cont’d Excretion: 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’d Reproduction: 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 Notes Representative 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’d Defenses: Cnidarians produce cnidocytes Contain a capsule (nematocyst) that, when “tripped”, shoots out. Traps or poisons prey.

The bitter sting…