Chapter 26 Sponges & Cnidarians Kingdom Animalia Chapter 26 Sponges & Cnidarians

What is an Animal? Multicellular Eukaryotic Heterotrophic Lack cell walls Sexual reproduction Movement (some) Specialization (some)

2 main categories of Animals Invertebrates: lack backbone or vertebral column. 95% of animals! Vertebrates: have a backbone of bone or cartilage. 5% of animals.

What animals do to Survive! There are 7 essential functions of animals: 1)Feeding: Herbivore = eats plants Carnivore = eats animals Omnivore = eats plants and animals Detritivore = feed on decaying organic material Filter Feeders = aquatic animals that strain food from water Parasite = lives in or on another organism (symbiotic relationship)

2)Respiration: Take in O2 and give off CO2 Lungs, gills, through skin, simple diffusion 3)Circulation: Very small animals rely on diffusion Larger animals have circulatory system 4)Excretion: Primary waste product is ammonia Liquid waste

5)Response: Receptor cells = sound, light, external stimuli Nerve cells => nervous system 6)Movement: Most animals are motile (can move) Muscles usually work with a skeleton 7)Reproduction: Most reproduce sexually = genetic diversity Many invertebrates can also reproduce asexually = to increase their numbers rapidly

Trends in Animal Evolution More complex animals tend to have: -high levels of cell specialization (Cells -->tissues -->organs --> organ systems) -bilateral symmetry -cephalization

Body Symmetry With the exception of sponges, all animals exhibit some type of body symmetry.

Cephalization Animals with bilateral symmetry usually display cephalization. Concentration of nerves in the front end (head) of body.

Body Cavities (coelom) Acoelomate Pseudocoelomate Coelomate Fluid-filled space that forms between the digestive tract and the outer wall of the body during development Can aid in movement and as a reservoir for transporting nutrients and wastes

Sponges Phylum Porifera (pore bearing) Body Plan – no symmetry acoelomate Filter feeding Some specialization of cells

3 Main groups of Sponges 1)soft – internal skeleton made of protein spongin 2)calcareous – skeleton made of spicules containing CaCO3. 3)silicate – skeleton made of spicules containing silica (glass) Spicule = spike shaped structure

Cnidarians Phylum Cnidaria Radial symmetry Acoelomate Have stinging tentacles 2 body forms Medusa polyp

Contain stinging cells called cnidocytes in their tentacles that contain coiled stingers called nematocysts that can shoot out & paralyze prey 

3 Classes of Cnidarians 1)Class Scyphozoa: Jellyfish

2)Class Hydrozoa: hydras, Portuguese man-of-war

3)Class Anthozoa: sea anemones & coral