Objectives: 1.Relate the form of specific structures to their function within this group. 2.Compare and contrast radial and bilateral symmetry. 3.Apply.

Objectives: 1. Relate the form of specific structures to their

function within this group.2. Compare and contrast radial and bilateral

symmetry.3. Apply how the evolution of the segmented body

led to increased motility

Sponges, Cnidarians, Comb Jellies, and

Marine Worms

Vocabulary

PoriferaAsymmetricRadial symmetrySessileOstaia Spongocoel Collar cellsChoanocytes Pinacocytes Archaeocytes

BuddingSexual reproductionAmphiblastulaCnidariansCnidocytesPolypMedusaHydrozoans Arthrozoans Scyphozoans Ctenophora

Sponges are simple asymmetric, sessile (non-moving) animals that lack tissues.

Structures found in Sponges:• Ostaia• Spongocoel• Collar cells• Choanocytes• Pinacocytes• Archaeocytes

Phylum Porifera:Sponges

Ostia: tiny holes in the sponge body through which large amounts of water circulate (oxygen and nutrients).

Spongocoel: A spacious cavity inside the sponge where water is held and then expelled trough the osculum.

Sponge feeding

http://www.youtube.com/watch?v=RmPTM965-1c&feature=related

Collar Cells: Have a flagellum that moves water through the sponges body and digests nutrients.

Pinacocytes: Provides the outer covering of the sponge.

Archaeocytes: resemble amoebas, and can move throughout the sponges body. They can form into any of cell types in the sponge body for growth and repair.

Reproduction in sponges

Sponges can reproduce both asexually and sexually.Budding: a group of cells on the outer surface of the

sponge develops and grows into a tiny new sponge.

Sexual reproduction: Sponges are hermaphrodites producing both egg and sperm.

Amphiblastula: a larval stage that spends time in the water column as plankton before settling and forming a new adult sponge.

sponge reproduction

Cnidaria: include, jellyfish, hydrozoans, anthozoans, and corals.

All Cnidarians possess Cnidocytes.Cnidocytes are specialized cells used not only to

capture prey but also for protection.

Phylum Cnidaria

Cnidarian Body Plan

Radial Symmetry: Body is arranged in a circle around a central axis, which can be divided into many planes.

Polyp: a benthic (bottom) dwelling Cnidarian characterized by a cylindrical body with an opening at one end (mouth).

Medusa: a free-floating stage that is commonly know as a jellyfish.

http://www.youtube.com/watch?v=elnpe5u4RZ0

Cnidocyte

There are more than 2 dozen different types of Cnida (NY-duh) that function for locomotion, defense, and capturing prey.

Nematocysts: a spearing type of cnida used to spear prey, that often include a toxin.

Example organism: Portuguese man-of-war.

Classes of Cnidarians

HydrozoansArthrozoansScyphozoans

Hydrozoans:

• mostly colonial organisms. • Form: Polyps. • Feeding Polyps:• Reproduction Polyps:• Examples: Hydra

Anthrozoans:

Anthrozoans:

Anthrozoans: polyps that secrete a skeleton made of calcium carbonate.

Examples: Sea anemones, and corals.

Scyphozoans:

• Scyphozoans: Jellyfish. Can generally exist in both the polyp stage and medusa stage. Some species have photoreceptors that allow them to determine if it is dark or light.

Combjellies: Like the Cnidarians, the exhibit radial symmetry. but, they lack Cnidocytes.

• some give off flashes of luminescence, possibly to attract mates of frighten predators.

Phylum: CtenophoraComb jellies