Jellyfish, Sponges, and Worms Chapter 15

Porifera Platyhelminthes spongin flame cells spicules Nematoda collar cells Annelida Cnidaria arteries ectoderm endoderm cnidocyte

What is an Animal? Eukaryotic Multicellular Has organized tissues Sexual reproduction Moves during at least part of its life Most animals Eat their food Have organs

What is an Invertebrate? An animal without a backbone Most animal species are invertebrates.

Invertebrate Skeletons Function Provide mechanical support for muscle attachment Maintain body shape May be external or internal May be made of limestone, silica, protein, or water

Phylum Porifera

Sponges “Pore animals” Sponges pump water through their pores Bring food and oxygen in Carry wastes out All sponges live in water. Most species live in the oceans. Adult sponges remain attached to an object. Embryonic sponges can swim about briefly.

Sponge Skeletons Spongin Spicules Made of a fibrous protein Soft and flexible Spicules Made of calcium carbonate or silica Pointed

Sponge Nutrition Filter feeders – filter water to obtain food Collar cells – line the central cavity Cells in a jellylike middle layer transport nutrients and other materials within the sponge

Phylum Cnidaria

Jellyfish Structure Two tissue layers – one cell layer thick Ectoderm – outer layer Endoderm – inner layer Gastrovascular cavity – digestion Mouth – only body opening Tentacles surround the mouth Nerve net throughout the body Control some contractile fibers

Jellyfish Structure Hydrostatic skeleton Primary support for the jellyfish A jellylike mass that fills the spaces between two tissue layers

Obtaining food Nematocysts – cells found in the ectoderm of the tentacles This paralyzes or kills the prey. The jellyfish uses contractile fibers to push its prey into its gastrovascular cavity. A trigger in the nematocyst can cause a thin tube to be forced out of the nematocyst. A poison is forced through the tube.

Digestion Digestive enzymes released by the endoderm break down the food. Substances which the jellyfish cannot digest are expelled through the mouth.

Movement A set of contractile fibers around the rim of the jellyfish contracts.

Jellyfish are mostly harmless, though some deadly varieties do exist, and have been described by marine experts as the cockroaches of the sea thanks to being tough, durable and able to survive in damaged environments. Students do not need to copy this.

Other Cnidarians Hydras, corals, sea anemones Capture prey with stinging tentacles and digests it in a central cavity. Possess radial symmetry Several different planes could divide an animal into equal halves.

Radial Symmetry

Phylum Platyhelminthes

Platyhelminthes Flatworms Bilateral symmetry – two equal sides Planarian – a free living flatworm found in freshwater streams and in soil

Nervous System Neurons – long, thin nerve cells Carry impulses from one point to another Nerve – a collection of neurons wrapped in protective coverings Ganglion – simple brain

Nervous System Neurons Nerves Ganglion Neurons – the wires that go to individual phones Nerves – the individual wires join to form cables Ganglion - switchboard

Simple Nervous System Longitudinal nerve runs down each side of the body Transverse nerves connect the longitudinal nerves

Nervous System Stimulus – something an organism can touch Planarians respond negatively to the touch of an object. In water, planarians normally travel upstream. They respond positively to the touch of flowing water.

Nervous System Planarians respond to chemicals in water. Eye spots For locating food Eye spots “Cross eyed worm” Sensitive to the presence or absence of light Does not see colors Normally, a planarian respond negatively to light (turns away).

Digestive System Body covering is one cell layer thick Cilia on the underside of the body help it to glide over underwater surfaces. Mouth – on the underside, near the middle of the body Intestine – long, branched cavity Extends to every area of the body

Digestive System Pharynx – muscular tube through which food is sucked into the intestine Non-digestible material is pushed out of the intestine through the mouth.

The thinness of a planarian’s body allows for gas exchange. Excretory system Flame cells – cilia move water and wastes through tiny tubes to the excretory pores

Bottom image is a land planarian, originally from southeast Asia Bottom image is a land planarian, originally from southeast Asia. Can reach up to 10 inches.

Tapeworms Common parasite of animals and humans Found in the digestive tract Head is equipped with hooks or suckers to attach it to the digestive tract. Most of the body consists of reproductive segments. Fill with eggs, are released, and exit in the animals feces.

Marine flatworms (polyclads) – order polycladidia

Other Flatworms

Review: Phyla Porifera Cnidaria Platyhelminthes Sponges Jellyfish Hydra Sea anemone Coral Platyhelminthes Flatworms Planerian Tapeworm

Support What is an invertebrate? Animal without a backbone What provides mechanical support for muscle attachment and maintains body shape? Skeleton Sponge? Spongin and spicules Jellyfish? Hydrostatic – jellylike substance

Review: Symmetry Cnidarian Radial Platyhelminthes Bi-lateral

Review: Miscellaneous Filter feeder Sponge Possesses longitudinal and transverse nerves and ganglia Planerian Uses nematocysts to obtain food Jellyfish

Phylum Porifera

Phylum Cnidaria

Phylum Platyhelminthes

Phylum Nematoda

Phylum Nematoda Roundworms – round, tubelike bodies Parasites and free-living Many are microscopic.

Ascaris May be found in the intestines of various animals

Ascaris Life cycle Eggs are released in an animal’s intestines. Eggs exit in the feces. Eggs are swallowed and hatch in intestine. Larvae burrow into the intestine walls and enter blood stream. The larvae reach the lungs, travel up the throat, and are reswallowed. The larvae grow into adult worms once back in the intestine.

Other Roundworms Parasites - hookworms, pinworms, trichina worms Vinegar eel – contribute to the development of the unique cider taste.

Phylum Annelida Polychaete in upper right hand corner (marine)

Phylum Annelida Segmented body plan Earthworms, leeches, tubeworms, and polychaetes Polychaetes include bristle worms, lungworms, fireworms and clam worms

The Body of an Earthworm Epidermis – covers the body Exchanges gases with the environment Must be kept moist for gas exchange Cuticle – protects the earthworm from harmful parasites and substances Secreted by the epidermis

Two muscle layers - Provide support and aid in movement When the circular muscles contract, the worm becomes longer and thinner. When the long muscles contract, the worm becomes shorter and wider. Bristles – aid in movement.

The Body of an Earthworm Two muscle layers Provide support Aid in movement Circular muscles Longitudinal muscles Bristles – aid in movement.

Sensory receptor – a structure that can sense a stimulus and start an impulse traveling along a neuron. More in the front end (An earthworm leads with it’s front end.) Large ganglia - Located in the third segment; Receives impulses from the front end Small ganglia - One in each segment; Found along the length of the nerve cord.

Earthworm’s Nervous System Sensory receptor – senses a stimulus and starts an impulse traveling along a neuron. Large ganglia Third segment Receives impulses from the front end Small ganglia One in each segment 2 suprapharyngeal ganglia attached to 1 subpharyngeal ganglion

An earthworm eats the soil as it forms tunnels. Most is indigestible Mouth – secretes fluids that moisten the soil. Upper lip – helps force food into its mouth. Pharynx secreted liquids lubricate food Muscle fibers help pull food into body Esophagus – carries food from the pharynx to the crop Crop – temporary storage Gizzard – muscular to grind food Intestine Enzymes break down food Nutrients are absorbed

Earthworm’s Digestive System An earthworm eats the soil as it forms tunnels. Most is indigestible

Mouth – secretes fluids that moisten the soil. Upper lip – helps force food into its mouth. Pharynx – Muscular organ pulls food into the body Esophagus – carries food from the pharynx to the crop Crop – temporary storage Gizzard – muscular to grind food Intestine Enzymes break down food Nutrients are absorbed

Earthworm’s Digestive System Anus - indigestible wastes leave the body Castings – wastes which form piles outside the earthworm’s tunnels.

Earthworm’s Circulatory System Closed circulatory system – the blood never leaves the blood vessels Open circulatory system – blood leaves the blood vessels before returning to the heart. Aortic arches – help control blood pressure Dorsal blood vessel – carries blood toward the aortic arches Ventral blood vessel – carries blood away from the aortic arches

Earthworm Respiration and Excretion Gas exchange occurs through skin. Capillaries lining skin receive and release gases. Excretion Nephridia – looped tubes that collect wastes from the blood Wastes leave the body through tiny pores