Ch 32 33 Sponges Cnidarians Ctenophores What is

Ch. 32 - 33 – Sponges, Cnidarians, & Ctenophores ® What is an invertebrate? ®An animal without a backbone. ® What are some examples? ® Animals are classified by their shape or symmetry. ® What is symmetry? ®Arrangement of body parts around a central axis.

Types of Symmetry ® 1. Asymmetrical – an organism without a definite shape. ®Ex. Sponge ® 2. Radial symmetry – an organism that can be divided into similar halves by any plane that passes through its longitudinal axis. ®Ex. hydra

® 3. Bilateral symmetry – is an organism that can be divided into similar halves by only one specific plane passing through its longitudinal axis. ®Ex. Humans, spiders, fish

Parts of an organisms’ surface ® 1. Posterior – lower end of the organism ®Ex. Feet of humans ® 2. Anterior – upper end of the organism. ®Ex. Head of a human ® 3. Dorsal – top surface of an organism. ®Ex. Back on a human ® 4. Ventral – bottom surface. ®Ex. Belly of a human

Organisms Development ®Organism develop from a zygote ®Then into an embryo ®Next is a blastula – a hollow ball of cells ®Final the blastula caves in and forms a depression called a blastopore. Once the blastula forms a blastopore it is now called a gastrula.

3 Germ Layers ® 1. Ectoderm – outside layer of cells ®Ex. Skin ® 2. Endoderm inside layer of cells ®Ex. Organs ® 3. Mesoderm – middle layer of cells ®Ex. Muscles

Porifera (phylum) ®Sponges ®No gastrula stage ®No true organs ®Sessile – don’t move ®Very colorful

Features of a sponge ®Osculum – top opening of a sponge ®A sponge is hollow in the middle ®The sponge’s hollow cavity is lined with collar cells, which have flagella. ®The collar cells are used to filter out food. Water and food enter the sponge through its pores then pass back out its osculum. Sponges are filter feeders.

®Amebocytes transport the food from the collar cells to the rest of sponge. ®Sponges have the ability to reproduce sexually or asexually; sponges carry both egg and sperm cells. ®Sponges reproduce asexually by producing buds called gemmules.

®Sponges have the ability to regrow missing parts. What is this called? ®Regeneration ®Most sponges have both sperm and egg cells, some have separate sexes. ®Hermaphrodite is an organism with both egg and sperm cells. ®Video Clip

Cnidaria (phylum) ®Example: jellyfish, hydra, coral ®Have endoderm & ectoderm layers ®All live in water (mainly marine) ®Have stinging cells called nematocyst ®Have a hollow gut ®Have tentacles

2 body shapes of Cnidarians ® 1. Polyp ®Sessile and vase-like shape ® 2. Medusa ®Swimming and bell shape ®All cnidarians use their tentacles to capture and paralyze their prey with a coiled stinger called a nematocyst.

® 3 Classes of Cnidarians ® 1. Hydrozoa – Hydra ®Both polyps and medusa shapes ® 2. Scyphozoa – jellyfish ®Mostly medusa ® 3. Anthozoa – corals ®Only as polyps

Hydrozoa (class) ® Hydra use their nematocyst to capture prey and engulf the whole prey into their gastro vascular cavity. They only have one opening (mouth and anus). ® Asexual reproduction of small buds occurs during warm weather. ® Sexual reproduction occurs mainly in the fall. ® Hydra are hermaphrodites. ® Video Clip

Scyphozoa (class) ®Mostly medusa ®Jellyfish have poisonous tentacles with nematocyst, also. ®Several humans been seriously injured and even killed from jellyfish off the coast of Australia. ®Video Clip

Anthozoa (class) ®Only polyp ®Sea anemones are polyps along rocks. ®Clown fish swim around in their tentacles. The clown fish is protected from the tentacles by a chemical in their skin that doesn’t allow the nematocyst to fire. ®Video Clip

3 main body cavities of organisms ® 1. Acoelomate – without a body cavity. ®Ex. Hydra, planaria ® 2. Pseudocoelomate – false body cavity. No true digestive system. The gut is suspended in fluid, not muscle. ®Ex. Roundworm ® 3. Coelomate – a true body cavity. ®Ex. Earthworm, insects, humans, ect.

Rotifera (phylum) ®Rotifers ®Free-swimming ®Marine and freshwater ®Cilia along its mouth, which is used to sweep food into its mouth. ®Looks like a spinning wheel as it moves. ®Video Clip