Annelids and Mollusks Animals – chpt 2 section 1 continued

Segmented Worms Phylum 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

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

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