Animals Invertebrates

Kingdom Animalia Around 9 or 10 million species of animals inhabit the earth About 800,000 species have been identified

General Traits of Animals A multicellular eukaryotic heterotroph Contain specialized cells  division of labor

Characteristics of Animal Life 1. Living things are organized 2. Living things are made up of cells 3. Living things metabolize 4. Living things grow 5. Living things respond 6. Living things reproduce 7. Living things evolve 8. Animals rely on other organisms for their nourishment

Trends in Animal Evolution Increase level of organization (cell  tissue  organ) Change in symmetry (asymmetrical radial  bilateral) Increase concentration of sense organs and nerve cells in the animal’s anterior region (cephalization)

Animal Symmetry Primitive animals are asymmetrical Cnidarians and echinoderms have radial symmetry Most animals have bilateral symmetry

Radial Symmetry Radial Symmetry applies to forms that can be divided into similar halves by more than two planes passing through it. Animals with radial symmetry are usually sessile, free-floating, or weakly swimming.

Bilateral Symmetry This is a shape that is two sided and produces a mirror image affect. Animals with bilateral symmetry usually has led to cephalization.

Anatomical Direction Ventral - the underside Dorsal - the back of the animal; the side opposite the ventral side. The vertebral column of vertebrates is on the dorsal side of the animal. Anterior - the head end Posterior - the end opposite the head end longitudinal plane - along a line from the head to the tail Transverse plane - along a line that is 90° to the longitudinal axis (see above)

Classification of Invertebrates

Phylum Porifera Sponges Origins

General Characteristics Literally means “pore-bearers” Asymmetrical or Radial symmetry Among the most ancient of all animals alive today Most are saltwater sponges Inhabit almost all areas of sea (eg. polar and tropic regions, low-tide and deep water) Adult sponges are sessile Multicellular animals Heterotropic No mouth, gut, specialized tissues or organ systems. Therefore, most biologists believe that sponges evolved from singe-celled ancestors separately from other multicellular animals.

Sponge Structure Water flows through the pores into the central cavity and out of the osculum. Collar cells draw out the food from the water as it flows through the pores.

Sponge’s Skeleton Sponges are composed of spicules and/or spongin to support their structure. The amebocytes are responsible for producing the (CaCO3 or SiO2) spicules and spongin (protein)

Form Body of sponge forms a wall around a hollow central cavity. Body wall has openings or pores through which a steady current of water moves through and enters the central cavity. Current of water powered by the flagella of cells called collar cells The current of water delivers food and oxygen to the cells and carries cellular waste products into the central cavity and out an opening at the top of the sponge known as the osculum. Gametes or larvae are also transported through the water. Spiny spicules interlock to form the skeleton of the sponge. Amebocytes produce spicules from either calcium carbonate or silica. Softer but stronger sponges have skeletons that consist of fibers of a protein called spongin Some sponges have skeletons made of both spongin and spicules.

Collar Cell Sponges are filter feeders that feed on microscopic particles of food. Food is drawn into the collar, become trapped and then engulfed by the cell (endocytosis) and enters a food vacuole.

All digestion is intracellular. Are filter feeders Food particles stick to collar cells, which engulf (endocytosis) and digest the particles. Amebocytes digest food particles that collar cells do not digest. They then deliver digested food to other parts of the sponge. All digestion is intracellular. Filter feeding made visible

Exception to filter feeding

Respiration, Excretion, Internal Transport System As water passes through the body wall, sponge cells obtain oxygen and release carbon dioxide. Metabolic wastes (eg. ammonia) are also released.

Reproduction - Asexual Gemmules are produced at the onset of winter. They are highly resistant to both freezing and drying Budding – when protrusions arise on the parent’s surface and breaks off to form a new sponge (exact copy of parent) Regeneration

Reproduction Sexual Eggs are kept inside the wall of the sponge, while sperm are released into the water flowing through the sponge and carried into the open water. Sperm flow into other sponges and are picked up by amebocytes to be carried to where the eggs are stored and fertilization occurs here. Zygote develops into larva and swims out of the osculum.

Reproduction Both asexual and sexual Asexual Gemmules are produced at the onset of winter. They are highly resistant to both freezing and drying Budding - when protrusions arise on the parent’s surface and breaks off to form a new sponge Sexual (Figure 26-12) Gametes (egg and sperm) are produced in the body wall sperm is released into the open water and enters a sponge wall via amebocytes fertilization occurs inside the body wall larvae swims out into the open water and eventually settles down to become sessile

Ecological Importance Many marine animals, such as worms, shrimp, snails and starfish live on, in and under sponges. Symbiotic relationships with blue-green bacteria, bacteria, or plantlike protists. Sponges important part of the diets of certain snails, starfish and fishes. Boring sponges help clean up the ocean floor. Used by humans in bathing. Sponges produce numerous compounds toxic to organisms. Many of these chemicals are powerful antibiotics used to fight disease causing bacteria, viruses and fungi.

Wild Ride through Sponges