Chapter 1: Invertebrates I: Sponges, Jellyfish, and Worms Unit 1: Concepts in the Animal Kingdom Chapter 1: Invertebrates I: Sponges, Jellyfish, and Worms

Introduction Over one million animal species Animal Multi-cellular Tissues Must obtain food rather than make own Most can move at some point in life cycle Eat food Have organs Reproduce sexually

What is an Invertebrate? Invertebrate: animal without a backbone Most animal species are invertebrates Skeleton: provides mechanical support and body shape Invertebrates have skeletons; often not internal skeletons made of bone Internal skeleton may be like: limestone, glass, protein, water

Sponges Sponges: “pore” animals—body made up of pores Phylum named: Poriferia Characteristics: All live in water Most live in oceans Only a few live in fresh water Adults unable to move—young sponges able to swim Made of spongin—fibrous protein, pointed spicules—calcium carbonate, or silica Some used as bath sponges

How a sponge eats: Filter feeders: filter water to absorb food Water enters pores of sponge Jellylike layer between outer and inner layer distributes nutrients in the sponge Water enters hollow central cavity of sponge Collar cells line the cavity; the flagella on the collar cells keep the water moving Water exist through large opening at top of sponge

Cnidarian—Jellyfish Jelly-like mass 2 Layers of tissues Hydrostatic skeleton: skeleton surrounded by water Most live in oceans Few found in freshwater Large central cavity surrounded by two tissues Tentacles

Jellyfish 2 Layers Ectoderm and Endoderm each one layer thick Gastrovascular cavity: used by the jellyfish to digest food Mouth: only body opening; food goes in/waste comes out Network of nerves No brain or collection of nerves Some muscle fibers controlled by nerves

Jellyfish Activities Tentacles have nematocysts (stinging cells) Stinging cell penetrates prey and poison is forced through thin tube Prey is paralyzed or killed Jellyfish uses tentacles to bring food to mouth Food digests in gastrovascular cavity/waste is expelled

Jellyfish Activities Tentacles not used for swimming Jellyfish mostly float around To swim Fish contracts and forces water out of gastrovascular cavity

Other Cnidarias All have tentacles with stinging cells Large central cavity surrounded by two tissue layers Example: hydra, corals, sea anemones Radial symmetry: several planes to divide Shape: Tube-like or umbrella shape Free living or permanently attached

The Planarian: A Type of Flatworm Characteristics: Phylum Platyhelminthes Bodies are flat Bilateral symmetry Free-living Live: freshwater, ocean, parasites, or soil

The Planarian: A Type of Flatworm Free-living Live in freshwater streams or soil The Planarian’s Nervous System Neurons: long thin nerve cells found throughout the body—carry impulses from one point to another Nerve: collection of neurons wrapped together in a protective coat Ganglion: “simple brain” switchboard for nerves several within body—control portion

The Planarian: A Type of Flatworm The Planarian Nervous System (cont.) Longitudinal nerve—runs down each side of body Transverse nerves—connects long. Nerves; ladder appearance Respond to Stimuli Stimulus—something an organism can sense Neuron receives stimulus, converts it to impulse, impulse travels through nerve to ganglion, ganglion sends response message

The Planarian: A Type of Flatworm Planarians Respond to: Touch Chemicals—find food in this way Light—two spots sensitive to light—”cross-eyed” worms—usually move away from light

The Planarian: A Type of Flatworm The Planarian’s Digestive System Body of planarian one layer thick Mouth—middle of the underside of its body Intestine—long branched cavity Gastroderm—cells that layer the intestine Eating: Extends pharynx (muscular tube) into mouth—sucks food into intestine; gastroderm secrete enzymes—digestion begins; nondigested materials exit through the mouth; intestines take nutrients to rest of body

The Planarian: A Type of Flatworm Oxygen and carbon dioxide is exchanged through thin skin Waste removed through series of tubes Flame cells—structure at the end of the tube that move waste Excretory pores—tiny holes that water and waste are excreted from the planarian

The Planarian: A Type of Flatworm Other Interesting Flatworms Examples: tapeworms, flukes, marine flatworms Tapeworms: common parasite found in the digestive tract Head has hooks or suckers to attach to wall of intestine Most of body eventually fills with eggs and released in host animal’s waste and spread to other animals

These individuals were photographed on a reef near the island of Guam. http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html

Copyright Marian K. Litvaitis, University of New Hampshire, 2005-2007

Roundworms Phylum Nematoda Round tube-like bodies Bodies tapered at one end Live: parasites or free-living Many microscopic

Roundworms Ascaris—A common Roundworm Parasite—lives in intestine of animals Eggs released in intestine—exist in feces When eggs are swallowed they hatch Young larvae enters blood stream—reach the lungs—at throat they are reswallowed Grow into adult worm in intestines

Roundworms Other Interesting Roundworms Example: Hook worms, pinworms, trichina worms Trichina worm found in pork Vinegar eel found in unpasteurized cider Other roundworms cause plant disease

The Earthworm and Other Segmented Worms Phylum Annelida Series of similar segments Examples: earthworms, leeches, tubeworms, scale worms, clam worms, lugworms

The Earthworm and Other Segmented Worms The Body of an Earthworm Epidermis—thin skin that covers body; used for gas exchange Cuticle—outer covering that protects worm Two muscle layers under cuticle—provide support and movement One layer—circles around body (long and thin) Second layer—long strips down body (shorter and wider) Bristles—tiny hairs on each segment that aid in movement

The Earthworm and Other Segmented Worms Earthworm’s Nervous System Sensory receptor—sense an impulse and send message along a neuron More sensory receptors at front than back Sensory Receptor in front —to neuron—to large ganglia in third segment Other sensory receptors—to neurons—to nerve cord—small ganglion at each segment Ganglia ‘interprets’ impulse and sends response message to neurons

The Earthworm and Other Segmented Worms The Earthworm’s Digestive System Earthworms eat soil as it makes tunnels Eats decaying leaves, fungi, and small creatures in dirt Digestive tract is long and straight

The Earthworm and Other Segmented Worms Mouth—dirt enters and is moistened (aided by upper lip) Food passes to pharynx—then to esophagus (tube like structure)—to crop Crop (temporary storage area)…then to gizzard…(mechanical digestion)..then to intestine Intestine—location of digestive enzymes to break down food—nutrients absorbed into blood steam here—nutrients carried throughout body by blood Indigestible parts—pass through anus—waste materials sometimes called castings

The Earthworm and Other Segmented Worms The Earthworm’s Circulatory System Continuous network of blood vessels Closed circulatory system—blood never leaves the blood vessel Dorsal blood vessel—along back of earthworm; acts as a heart Five aortic arches Ventral blood vessel—along the bottom of the worm

The Earthworm and Other Segmented Worms The Earthworm’s Circulatory System Blood passes from arteries to smaller capillaries to the veins Veins take blood back towards the heart

The Earthworm and Other Segmented Worms The Earthworm’s Respiratory and Excretory System Exchanges carbon dioxide and oxygen through skin In emergency can go several hours without oxygen In storms come to surface because borrows fill with water Nephridia—tiny looped tubes that collect wastes from worm’s blood

Organization of Animals Cells Tissues Organ Systems

How do living things get food? Heterotrophs: Must get their food from another source Autotrophs: Make their own food

How do animals reproduce? Asexual Reproduction: same genetics as parents Sexual Reproduction: half genetics from mom and half the genetics from dad

What do animals eat? Herbivore: eats plants Carnivore: eats animals Omnivore: eats both plants and animals

Classification of Living Things

Symmetry Radial: Many lines of symmetry Bilateral: One line of symmetry