BIOL113 L25

Sponges

Sessile with porous bodies, choanocytes, loose federations of cells, lack nerves or muscles, and capable of extensive regeneration.

Sponges Sensing

Individual cells can sense and react to changes in the environment.

Spongocoel

Central cavity in sponges where water is drawn through the pores and flows out through the osculum.

Sponge Feeding

Most sponges are suspension feeders, collecting food particles from water passing through food-trapping equipment.

Sponge Body Components

Consists of two cell layers separated by a gelatinous region, the mesohyl, with wandering amoebocytes.

Sponge Reproduction

Most sponges are hermaphrodites, producing both sperm and eggs, with zygotes developing into swimming larvae.

Cnidarians

Oldest eumetazoan clade with radial symmetry and diploblastic embryos.

Cnidarian Body

Radial symmetry, a gastrovascular cavity, and cnidocytes.

Cnidarian Species

Over 10,000 living species, mostly marine.

Cnidarian Body Variations

Sessile polyp and floating medusa are two variations of the basic body plan.

Cylindrical Polyps

Hydras and sea anemones capture prey by adhering to the substratum and extending tentacles.

Medusas

Flattened, mouth-down versions of polyps in cnidarians that drift passively.

Cnidarian Prey Capture

Tentacles with cnidae capture prey and push food into the gastrovascular chamber for digestion.

Cnidae Function

Organelles in cnidarians that inject poison or entangle prey.

Gastrovascular Cavity

Acts as a hydrostatic skeleton in cnidarians.

Cnidarian Movements

Controlled by a noncentralized nerve net and simple sensory receptors.

Cnidaria Classes

Divided into Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa.

Hydrozoans Life Cycle

Alternating polyp and medusa forms, as in Obelia.

Hydras

Among Hydrozoa, hydras exist only in the polyp form.

Scyphozoa Life Cycle

Medusa generally prevails in the life cycle of Scyphozoa.

Coral Animals

Solitary or colonial forms in Anthozoa that secrete calcium carbonate skeletons.

Coral Reefs

Built by polyp generations, providing habitat for diverse marine life.

Coral Reefs Damage

Suspected to be caused by global warming.

Box Jellyfish

Belong to the class Cubozoa with a medusa and small polyp stage in their life cycle.

Box Jellyfish Features

More developed nervous system and functioning eyes compared to Scyphozoa.

Flatworms

Acoelomates lacking a body cavity, with around 20,000 species.

Flatworm Habitats

Found in marine, freshwater, and damp terrestrial habitats.

Flatworm Mesoderm

Contributes to complex organs, organ systems, and true muscle tissue.

Flatworm Waste Removal

Nitrogenous wastes are removed by diffusion.

Planarians

Move using cilia on the ventral epidermis, gliding on a film of mucus they secrete, and reproduce asexually through regeneration and sexually through hermaphroditic cross-fertilization.