What is an Animal? Invertebrates

1. What is an Animal?Invertebrates

2. Characteristics of Animals • Biologists have identified over 1 million animal species • All animals are multicellular and are heterotrophs • Contain tissues, organs, and organ systems • Animals typically reproduce sexually • Most animals are capable of movement

3. How do Animals Meet Their Needs? • Need water because all chemical reactions (such as respiration) require water • Need food for growth and energy • Require oxygen to release energy from food • Respond to their environments through various adaptations

4. Animal Adaptations • Herbivores- animals that eat only plants • Teeth with broad, flat surfaces • Carnivores- animals that eat only other animals; are predators • Sharp, pointed teeth • Omnivores- animals that eat both plants and animals • Prey- animals that are eaten by predators; have hard shells, spiny skin, stingers, claws, stench to avoid being eaten.

5. Sponges • Live in aquatic environments, such as the ocean, lakes, and rivers • Remain in one location- attached to hard surfaces • Have bodies like bags that are pierced with openings known as pores • Bodies supported by a network of spikes • Examples: asconoids, synconoids

6. Sponges • Are filter-feeders: water passes through the sponge, carrying with it protists and bacteria • Get oxygen from the water via diffusion • Reproduce both sexually and asexually • Budding • Produce egg and sperm that are carried by water • Fertilized egg develops into a larva • Larva: an immature of an animal that looks very different from the adult

7. Cnidarians • Live in oceans • Having stinging cells and a hollow, central cavity • Carnivores that use stinging cells to attack and defend • Have specialized tissues • 2 body shapes • Polyps- vase-like shape, attaches to a hard surface • Medusa- bowl-like shape, free-swimming

8. Cnidarians • Obtain food by stinging prey and using tentacles to draw into the central cavity • Digestive system has only one opening • Reproduce sexually and asexually • Budding • Some species have both sexes within one individual • Other species have separate sexes

9. Cnidarians • Examples: jellyfish, sea anemones, corals

10. Worms • Long, narrow bodies without legs • Have head and tail ends • Simplest organism with a brain • Contain organ systems • Have quick responses • Three main phyla- flatworms, roundworms, segmented worms

11. Worm Reproduction • Some species have separate sexes • Some species have both male and female organs, but usually do not self-fertilize • Some species can reproduce asexually, by breaking into pieces • Some species can undergo regeneration- the ability to regrow body parts

12. Flatworms • Phylum Platyhelminthes • Have flat bodies • Most are parasites that obtain food from a host • May live in a host, or damp soil, pond rocks, or oceans • Digestive system with only one opening • Examples: tapeworms, planarians

13. Roundworms • Phylum Nematoda • Live in any moist environment, including soils and sand • Have cylindrical bodies • Have a digestive system with 2 openings

14. Segmented Worms • Phylum Annelida • Live in nearly all environments • Bodies made up of many linked segments • Have a closed circulatory system • Scavengers that eat decayed plant and animal remains • Obtains oxygen through its skin • Examples: earthworms, leeches

15. Mollusks • Invertebrates with soft, unsegmented bodies that are often protected by hard shells • Have a mantle: thin layer of tissue that covers their internal organs • Remove oxygen from the water via gills • Have a radula: a flexible ribbon of teeth • Reproduce sexually • Most live in water, marine and freshwater

16. Mollusks • Examples: gastropods such as snails, bivalves such as clams, oysters, mussels and cephalopods such as octopuses, squids

17. Types of Mollusks • Gastropods- have a single shell, or no shell at all • Live in almost all environments • Bivalves- have two shells held together by hinges and strong muscles - most are filter-feeders - live in watery environments - produce pearls • Cephalopods- have feet adapted to form tentacles around their mouths; variety of shells - capture food with tentacles - complex nervous system with large eyes - live in the ocean

18. Arthropods • Invertebrates that have external skeletons, segmented bodies, and jointed attachments (wings, mouthparts, legs) • Open circulatory system • Reproduce sexually with separate sexes and internal fertilization • Covered by an exoskeleton- waxy outer covering that protects the animal and helps prevent evaporation of water • Live on land and in the water

19. Arthropods • Bodies are divided into segments • Have jointed appendages to help with flexibility and movement • Antenna: an appendage on the head that contains sense organs • Examples: - crustaceans such as crabs, shrimp - arachnids such as spiders, ticks - centipedes and millipedes - insects such as butterflies, cockroaches, and bees

20. Arthropods

21. Insect Life Cycles • Begin life as tiny, hard-shelled, fertilized eggs • Undergoes one of two types of metamorphosis • Complete metamorphosis 1. Egg- female lays fertilized eggs 2. Larva- eggs hatch into wormlike larva 3. Pupa- insect enclosed in a protective covering 4. Adult- is very different from the larval stage • Gradual metamorphosis 1. Egg- female lays fertilized eggs 2. Nymph- look like miniature adults, no/little wings 3. Larger Nymph- insect molts 4-5 times as it grows 4. Adult- emerge from final molting with complete wings

22. Echinoderms • A radially symmetrical invertebrate that lives on the ocean floor • Skin is supported by a spiny internal skeleton (endoskeleton) • Body parts are arranged in multiples of 5 • Have a water vascular system- fluid filled tubes that help the echinoderm move and capture food • Reproduce sexually as separate sexes with external fertilization • Can regenerate arms

23. Echinoderms • Examples: sea stars, brittle stars, sand dollars, sea urchins, sea cucumbers