Chapter 23 Animals: The Invertebrates

Characteristics of Animals 1. Multicellular. Cells are usually arranged in organs or organ systems 2. Heterotrophs 3. Require oxygen to perform aerobic respiration

4. Most are motile at some point in the life cycle 5. Life cycle includes some sort of embryonic development 6. Mostly reproduce sexually (some asexually)

Radial Symmetry No clear front or rear No clear front or rear Body parts are arranged around a central axis Body parts are arranged around a central axis

Bilateral Symmetry Organism is the same on either side of one plane of symmetry Organism is the same on either side of one plane of symmetry Has a true front and rear Has a true front and rear

Phylum Porifera - Sponges Animals with no symmetry, no tissues or organs. Animals with no symmetry, no tissues or organs. Range in size from tiny (like a fingernail) to large enough to sit in Range in size from tiny (like a fingernail) to large enough to sit in Engulf particles to feed (phagocytosis) Engulf particles to feed (phagocytosis) Can reproduce sexually with a larva or asexually by fragmentation Can reproduce sexually with a larva or asexually by fragmentation

Sponges

Phylum Cnidaria Jellyfish, sea anemones, coral Jellyfish, sea anemones, coral All are aquatic – most are ocean dwelling All are aquatic – most are ocean dwelling Have tissues Have tissues Have nematocysts – “stinging darts” Have nematocysts – “stinging darts” Reproduce sexually Reproduce sexually Have a nerve net for stimulation Have a nerve net for stimulation

Jellyfish, Corals, Hydra

Phylum Platyhelminthes - Flatworms Turbellarians, Flukes, and Tapeworms Turbellarians, Flukes, and Tapeworms Have a simple digestive system – absorb food from a host Have a simple digestive system – absorb food from a host Body is flattened Body is flattened Most are hermaphrodites, but will reproduce sexually with another flatworm Most are hermaphrodites, but will reproduce sexually with another flatworm

Flatworms Sea slugs

Phylum Nematoda - Roundworms Thrive nearly everywhere Thrive nearly everywhere Have a complete digestive system Have a complete digestive system Have a partial body cavity where reproductive organs are found Have a partial body cavity where reproductive organs are found Most are free-living, with few parasitic species Most are free-living, with few parasitic species

Roundworms Ancyclostoma duodenale (hookworm)

Phylum Annelida – Segmented Worms Segmented worms – segments are repeating body sections Segmented worms – segments are repeating body sections Many have setae (small hair like bristles) to help them move through soil Many have setae (small hair like bristles) to help them move through soil Have a complete gut, rudimentary brain (with nerve cord), and circulatory system Have a complete gut, rudimentary brain (with nerve cord), and circulatory system

Earthworms and Leeches

Phylum Mollusca Octopus, squid, clams, scallops, snails, slugs, oysters Octopus, squid, clams, scallops, snails, slugs, oysters Most have a hard shell with a soft body Most have a hard shell with a soft body Have well developed organ systems Have well developed organ systems Have a brain Have a brain

Octopus, Squid, Snail, Oyster

Phylum Arthropoda (I accidently left this off – add it!) Insects, crustaceans, arachnids Insects, crustaceans, arachnids Hardened exoskeletons Hardened exoskeletons Jointed appendages Jointed appendages Respiratory Structures Respiratory Structures Sensory Structures Sensory Structures Division of labor Division of labor

Class Arachnida

Class Insecta

Class Crustacea

Phylum Echinodermata Sea urchins, star fish Sea urchins, star fish Have spines or plates of calcium carbonate Have spines or plates of calcium carbonate Well developed skeleton Well developed skeleton No brain, but nervous system is present No brain, but nervous system is present Water vascular system to deliver water to tube feet for movement Water vascular system to deliver water to tube feet for movement

Sea Stars, Sea Urchins Class Asteroidea

Phylum Chordata Includes some invertebrates and ALL vertebrates Includes some invertebrates and ALL vertebrates Subphylum Vertebrata – all vertebrates are in this subphylum Subphylum Vertebrata – all vertebrates are in this subphylum

Works Cited ersity/lower%20invertebrates/hydra_l.s._X_40.jpg ersity/lower%20invertebrates/hydra_l.s._X_40.jpg ersity/lower%20invertebrates/hydra_l.s._X_40.jpg ersity/lower%20invertebrates/hydra_l.s._X_40.jpg Lab10/Ancylostoma_male_10X.jpg&imgrefurl Lab10/Ancylostoma_male_10X.jpg&imgrefurl Lab10/Ancylostoma_male_10X.jpg&imgrefurl Lab10/Ancylostoma_male_10X.jpg&imgrefurl