Animals Chapter 2 Sponges Cnidarians and Worms Sections

Animals Chapter 2 Sponges, Cnidarians, and Worms Sections 1 and 2

Definitions • Nerves – carry signals throughout the body • Ganglia – groups of nerves bundled together. Animals can have a brain and ganglia or just have ganglia depending on how advanced the animal is • Gut – pouch lined with digestive enzymes • Coelom – cavity that allows organs such as the gut, heart etc to work without interference from body movement

Coelom

Ganglion

Symmetry

Sponges • Phylum Porifera • 1 st animals on earth

Phylum Porifera • • Simplest of all animals Asymmetrical No head, nervous system, gut or coelom Spicules are needle-like splinters that make up the skeleton • If cells are separated, they can come back together • Both asexual and sexual reproduction

Sponge Anatomy • Pores - used to pump water into sponge • Collar Cells – filters particles of food from water and digests them • Osculum – hole at the top of the sponge

Anatomy of a Sponge

Cnidarians • • Jellyfish Hydra Sea anenome corals

Phylum Cnidaria • • Radial symmetry Complex tissues Gut Nerve net and nerve ring in medusa form If cells get separated, they come back together Tentacles – covered with nematocysts Nematocysts – stinging cells Sexual and asexual reproduction

Body Forms • Medusa – free swimming, mushroom shaped • Polyp – vase shaped, attached to a surface • Most spend life as polyps but some are born polyps and turn into medusas

Flatworms Platyhelmenthes • Planaria • Flukes • Tapeworms

Characteristics • • • Bilateral symmetry Nervous system Ganglia acts as a brain Sensory lobes to detect light and food Planaria have a gut Fluke and tapeworms are parasites and have no gut

Reproduction of Fluke

Reproduction of Tapeworms • Sexual • Can go from uncooked meat to human

Roundworms - Nematoda

Roundworm • Pseudocoelom – tube within a tube • Bilateral symmetry • Can pick up through the soles of feet, through dirty hands, through some foods

Segmented Worms Annelida • Includes earthworms, bristle worms and leeches • Can live in water or on land

Earthworms, Bristle Worms, Leeches Earthworms – aerate soil (makes tunnels) to allow water and air in, break down organic matter into elements that can be used Bristle Worms – all live in water Leeches – can be scavengers, predators or parasites, and can be used in medicine

Next… • Earthworm dissection • Earthworm questions powerpoint

Mollusks • Phylum Mollusca • Soft bodied usually with a shell or shells • Three classes: • Gastropods – snails and slugs • Bivalves – 2 shells- clams, mussels, etc. • Cephalopods – squid and octopus

Similarities Between Mollusks

Feeding • Different depending on species: • Gastropods have a radula which is like a really rough tongue and scraps algae, leaves etc. • Bivalves filter feed • Cephalopods use tentacles to grab prey

Circulatory System • Most mollusks have an open system • Open system - A simple heart pumps blood into sinuses • Cephalopods have a closed system • Closed system – blood is circulated through a closed loop

Brains • Most mollusks have ganglia spread throughout their body • Cephalopods have a brain where all of the ganglia are connected

Next • Squid Dissection