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