Invertebrates I: Sponges, Jellyfish, and Worms

15A What is an Invertebrate? Prefix –in means “not” or “without” Vertebra is one of the bones along the back of an animal An INVERTEBRATE is an animal without a backbone Most animal species are invertebrates Skeleton – a structure in animals and humans that provides mechanical support for muscle attachment and maintaining body shape

15A What is an Invertebrate? Although an invertebrate does not have a backbone, it does have a skeleton It may have either an internal or external skeleton made of minerals similar to limestone, glass, protein, and even ordinary water

15A Review 1. About how many animal species are there? 2. Why is a bee considered an invertebrate? 3. Besides bone, list three substances that could compose an animal's skeleton.

15B Sponges Sponges are “pore animals” Their existence depends on the number of pores in their bodies through which they pump water that brings food and oxygen in and carries wastes out Phylum Porifera All sponges live in the water, and most live in oceans Adult sponges remain permanently attached to solid objects and are unable to move place to place, BUT embryonic sponges can swim around briefly

15B Sponges Have skeletons made of spongin, of spicules, or of both Spongin - is a flexible, fibrous protein Spicules – stiff, pointed little spikes made of calcium carbonate or silica Be familiar with Figure 15B-1 on page 269 Collar cells – cells lining the central cavity, which possess flagella Sponges are often called filter feeders because they filter water to obtain food

15B Review 1. To what sponge characteristic does the name Porifera refer? 2. If adult sponges are permanently attached to solid objects, how can they colonize other areas? 3. What and how do sponges eat?

15C The Jellyfish: A Cnidarian Jellyfish belong to the phylum Cnidaria They have tentacles with stinging cells They are usually found in oceans; though a few can be found in freshwater 15C.1 The Body of a Jellyfish The Jellyfish has a hydrostatic skeleton. Has a large central cavity surrounded by two tissue layers. Layers are called the ectoderm and the endoderm. Inside the endoderm is the gastrovascular cavity were the Jellyfish digests its food. The Jellyfish has no brain, just a network of nerves.

15C The Jellyfish: A Cnidarian 15C.2 Jellyfish Activities The Jellyfish can defend itself and paralyze its prey with nematocysts (special cells found in the ectoderm). The Jellyfish uses weak fiber muscle fibers in its tentacles to push the prey into its gastrovascular cavity. Digestive enzymes are released by cells in the endoderm to break down the food in the gastrovascular cavity. Jellyfish do not use their tentacles to swim. Most of the time jellyfish just float. When they do swim, a set of muscle fibers around the rim of the jellyfish contracts.

15C The Jellyfish: A Cnidarian 15C.3 Other Interesting Cnidarians Hydras, corals, and sea anemones are also cnidarians. The Portuguese man-of-war is a dangerous cnidarian that is actually a floating colony containing many specialized polyps. The bodies of cnidarians have radial symmetry. Radial symmetry means that they can be divided into equal halves by any plane along the length of the organism. Cnidarians may be either free-floating or permanently attached to a solid object.

15C Review 1. What is the supporting material in a jellyfish's skeleton? 2. Where do jellyfish digest their prey? 3. What is the soft body of a coral animal called?

15D The Planarian: A Flatworm Flatworm members = flat! Bilateral symmetry (can be divided into two equal halves – like a mirror image) Phylum Platyhelminthes It is a free-living (not a parasite) flatworm that can be found in freshwater streams and in soil. Flatworms can be found in the oceans, in fresh water inside other animals as parasites, or in the soil.

15D The Planarian: A Flatworm 15D.1 The Planarian’s Nervous System Neurons are long, thin nerve cells found throughout the body of an animal or human. Most animals control their bodies through neurons. A collection of neurons wrapped in protective coverings is called a nerve. Many invertebrates have nervous systems that are fairly complex and require some coordination. An invertebrate’s “coordination center” is a ganglion, sometimes called a simple brain.

15D The Planarian: A Flatworm 15D.1 The Planarian’s Nervous System The planarian has a simple nervous system. A longitudinal nerve runs down each side of its body. A series of transverse nerves connects the longitudinal nerves. The planarian’s ganglia coordinate its responses to stimuli. A stimulus is something an organism can sense. Planarians respond differently to different things such as touch, the flow of water, chemicals in water, and light.

15D The Planarian: A Flatworm 15D.2 The Planarian’s Digestive and Excretory Systems. The planarian’s body covering is a tissue that is one cell- layer thick. Cilia on the underside of the planarian help it glide over underwater surfaces. The mouth of he planarian is on its underside, near the middle of its body. Just inside the mouth is a long branching cavity called the intestine which is lined with a layer of cells which is called the gastroderm. The planarian eats by extending a muscular tube called the pharanx through the mouth and sucking food into the intestine.

15D The Planarian: A Flatworm 15D.2 The Planarian’s Digestive and Excretory Systems. The planarian’s food is digested in the gastroderm. Nondigestible material is pushed out of the intestine though the mouth. The planarian’s intestines extend to every area of the worm’s body and food is moved throughout the intestine by the twisting movements of the planarian and by flagella. The planarian has a mass of cells between its body covering and gastroderm. Some of the cells are specialized for particular functions. The planarian’s body is very thin. This allows the animal’s cells to exchange oxygen and carbon dioxide directly with the environment.

15D The Planarian: A Flatworm 15D.2 The Planarian’s Digestive and Excretory Systems. The planarian gets rid of its waste products through a system of tiny tubes. At the end of these tubes are structures called flame cells. The cilia at the end of these structures look like tiny flames. These cilia move water and wastes through the tubes to tiny holes called excretory pores. Here the water and wastes are excreted from the planarian.

15D The Planarian: A Flatworm 15D.3 Other Interesting Flatworms Some other common flatworms include tapeworms, flukes and marine flateworms. Tapeworms (a common parasite of animals and humans) are found in the digestive tracts of various animals. A Tapeworm has a head equipped with hooks and/or suckers to attach it securely to the digestive tract. It is nourished by absorbing dissolved food that is passing through this digestive cavity.

15D Review 1. What type of symmetry does a planarian have? 2. How many longitudinal nerves does a planarian have? 3. Where is the mouth of a planarian?

15E Roundworms 15E.1 Ascaris – A Common Roundworm In the phylum Nematoda Have round, tubular bodies and are tapered at each end Some are serious parasites of humans, animals, and plants; others are free-living Many are microscopic; some may grow to be 30cm (12in) long! The adult Ascaris can be found in the intestines of various animals

15E Roundworms 15E.1 Ascaris – A Common Roundworm The tiny eggs are swallowed and young larvae burrow in the intestine walls and enter the blood stream They eventually reach the lungs and travel up the throat and are reswallowed In the intestine again, larvae develop into adults Humans, cats, dogs, and various farm animals can have round worms

15E Roundworms 15E.2 Other Interesting Roundworms Other serious roundworm parasites include hookworms, pinworms, and trichina worms Trichina often form cysts containing larvae in the muscle tissue of pigs Vinegar eel – appear as tiny threads in unpasteurized vinegar and cider products (not parasitic thankfully!) Other roundworms cause serious plant diseases

15E Review 1. Name the phylum that includes roundworms 2. Where does an adult Ascaris normally live? 3. Are roundworms parasites of animals only? Explain.

15F Segmented Worms 15F Segmented Worms The earthworm has a long, slender body made of a series of similar segments The segmented body plan is what distinguishes earthworms from others Phylum Annelida Leeches, tube worms, scale worms, sandworms, and fireworms also belong to this group

15F Segmented Worms 15F.1 The Body of an Earthworm Covering the earthworm’s body is a thin, skin called an epidermis The epidermis exchanges gases (carbon dioxide and oxygen) with the environment. It also secretes a thin outer coating called the cuticle The cuticle protects the earthworm from harmful parasites and substances Cuticle must be thin and its epidermis kept moist for gas exchange

15F Segmented Worms 15F.1 The Body of an Earthworm Under the epidermis, are two muscle layers They provide support and help it move One layer is arranged in circles around the earthworm’s body When these muscles contract, the worm becomes longer and thinner The other muscle layer is arranged in long strips running from the head to the tail When these muscles contract, the earthworm becomes shorter and wider

15F Segmented Worms 15F.1 The Body of an Earthworm The earthworm moves by using its muscles and tiny bristles on each segment It moves forward by extending the bristles on its rear segments into the soil Once the rear segments are anchored, it contracts its circular muscles – which causes it to become long and thin, pushing its front end forward Then the worm releases the rear segments and extend the front half into the soil, pulling itself forward by contracting its long muscles

15F Segmented Worms 15F.2 The Earthworm’s Nervous System There are many sensory receptors on the body of the earthworm Sensory receptor – a structure that can sense a stimulus and then start an impulse traveling along a neuron Some of its sensory receptors are sensitive to chemicals in the soil, others to light, and some to temperature and other conditions There are more sensory receptors at an earthworm’s front end because it leads with its front end They help the worm to sense whether it is approaching food or danger so that it can react accordingly

15F Segmented Worms 15F.2 The Earthworm’s Nervous System The earthworm’s neurons carry impulses from the sensory receptors in the front of the worm to two large ganglia in the third segment Sensory receptors in other areas send impulses to the nerve cord in the lower half of the worm Nerve cord – a bundle of neurons that begins at the two large ganglia and continues to the tail of the worm Along the nerve cord there is one small ganglion in each segment of the worm

15F Segmented Worms 15F.2 The Earthworm’s Nervous System The ganglia interpret the impulses from the sensory receptors, and the worm decides what to do with them Interprets and decides describe the worm’s response to stimuli – but these words are not good words because they imply intelligence Earthworms have very little intelligence Neurons carry impulses to muscles, bristles, and other structures that will enable the earthworm to respond properly

15F Segmented Worms 15F.3 The Earthworm’s Digestive System often eats the soil as it forms tunnels Most of the soil is indigestible, but within the soil are decaying leaves, fungi, and small creatures Has a long, straight digestive tract At various points along the tract, there are enlargements, constrictions, infoldings, and glands Each has a separate function The mouth secretes fluids that moisten the soil as it enters Look closely: you may notice an upper lip! Used to force food in their mouth

15F Segmented Worms 15F.3 The Earthworm’s Digestive System From the mouth, the soil passes to the pharynx Then to the esophagus – a tubular passageway that carries food from the pharynx to the crop Crop – looks like a swelling in the digestive tract Food leaving the crop passes into the gizzard – another bulge in the digestive tract Then it goes from the gizzard to the intestine Indigestible parts pass through the intestine and leave the digestive tract through the anus Castings – wastes that accumulate in piles outside the tunnels

15F Segmented Worms 15F.4 The Earthworm’s Circulatory System A continuous network of blood vessels Closed Circulatory System – when blood never leaves the blood vessels Dorsal blood vessel – along the back – acts as a heart It pumps blood forward to the five sets of aortic arches Ventral blood vessel carries blood throughout worm Capillaries – blood passes through arteries and enter tiny blood vessels called capillaries Blood flows from arteries through capillaries to veins In closed systems, blood is carried toward the heart

15F Segmented Worms Path of blood flow in a closed circulatory system: 15F.4 The Earthworm’s Circulatory System Path of blood flow in a closed circulatory system: Veins heart  arteries  capillaries  Veins

15F Segmented Worms 15F.5 The Earthworm’s Respiratory and Excretory System Does not have special respiratory structures Gas exchange through the moist skin Excretory tubules – where wastes collect an are passed out of the body through tiny pores

15F Review 1. Name three members of phylum Annelida besides earthworms 2. In which part of the earthworm's digestive system does mechanical digestion occur 3. How does an earthworm breathe? 4. How can our study of earthworms help us exercise dominion over the earth?

Invertebrates II: Mollusks, Arthropods, and Echinoderms

16A Mollusks Mollusks include the following animals: Clams Snails Slugs Octopuses Phylum Mollusca Phylum with the 2nd highest number of species and is very important to the environment Also important to man Food (clams, oysters, and scallops) Make things (pearls, mother-of-pearl buttons) Pests or parasites (slugs and snails can be pests)

A Mollusk without a shell 16A.1 The Octopus A Mollusk without a shell It’s body lacks structure to give it firm support It does have many muscles Eight arms (tentacles) that has muscle to help it move its arms in any direction On the underside of each arm, there are suction disks, which allow it to grasp items. Food captured in its arms can be moved to its mouth (located under the head)

16A.1 The Octopus The suction disks can also be used to fasten itself to things If an arm is destroyed or severed, it has the ability to regenerate (grow) a replacement! Although it hunts live food (crabs, lobsters, and shelled mollusks), it appears to be a timid animal If it senses danger, it hides It moves by gliding along in the water – but it is a slow creature In order to move quickly, it forces water through a muscular tube called a siphon This jets the octopus through the water Occasionally, when frightened, it will release an inky black fluid into the water to serve as a “smoke screen”, allowing it to get away.

16A.1 The Octopus The octopus has a thin, flexible skin that helps its body hide more easily in the cracks between rocks and the ocean floor It can “pour itself” into gaps and completely change its body shape It can also cause different colored cells on their skin to spread out their pigments, helping to change colors! It can become visible against almost any background Its colors may also reflect its level of stimulation If it is startled, it usually turns pale; when it is excited, it often turns red

16A.2 The Clam A Mollusk with a shell It produces a shell to protect and cover their bodies Clams, mussels, and scallops produce two shells hinged together – called bivalves Snails and conchs produce a single shell - called univalves

16A.2 The Clam The clam’s soft body is covered with a thin skin called a mantle Outside of this skin is where material is produced that hardens to become a shell As it grows, it adds layers to the shell The newest part of the shell is thinnest It also has powerful muscles that keep its shell tightly closed When a clam moves, it sends out a muscular FOOT It is hatchet shaped and is pushed into the sand and expanded The muscles contract to shorten the foot and pull the animal and shell forward

16A.2 The Clam They do not hunt for their food Clams are filter feeders They dig into the sand and send two tubes called siphons out to the water. The siphon is used to draw water into the shell, where tiny food particles are filtered out The other siphon sends the water away from the clam to remove wastes

16A Review 1. Name a Mollusk that is edible 2. What does an octopus use its siphon to do? 3. What part of the clam's body manufactures its hard shell?

16B Arthropods

16B Arthropods Phylum Arthropoda They serve as: The most species of any animal phylum The insect class is the largest class within this phylum Almost a million species of insects identified Many play significant role in our world, especially insects They serve as: Pollinators, decomposers, crop eaters, disease carriers, and parasites Animals in this phylum have: Exoskeletons, and jointed appendages such as legs and antennae Exoskeleton – hard, nonliving, outer covering that supports and protects the animal

16B.1 A Typical Insect’s Body Insects typically have three sections to their bodies: Head Thorax (middle part) Abdomen They also have three pairs of legs (6 total) Caterpillars appear to have more than three pairs, but actually they are not real legs Most insects have two pairs of wings, although some may have none or one pair Compound eyes: their eyes have thousands of small sections Grasshoppers see in a mosaic of smaller images See page 286 for picture

16B.2 Body Systems in the grasshopper Grasshoppers have blood and a circulatory system (like all arthropods) Blood – is a fluid tissue made up of cells floating in liquid The main function of blood – to carry substances to and from all parts of the body Heart – muscular organ that pumps blood to all body cells Has a series of small tubular hearts located just under its exoskeleton (see explanation p. 289) Artery – blood vessels that carry blood AWAY from the heart Open Circulatory System – Blood that does not remain in the blood vessels

16B.2 Body Systems in the grasshopper The blood is colorless, not red It carries mostly food and wastes and has little to do with oxygen transport Tracheae – where insects receive oxygen and release carbon dioxide They are tiny elastic tubes that branch throughout the insect Air is pumped in and out of these twenty small openings called spiracles Insecticides – chemicals only harmful to insects and not other living things As blood circulates, it collects wastes These wastes are filtered out of the blood and collected by thread-like excretory tubules

16B.3 Insect Life Cycles Insects go through one of two different life cycles: Some molt throughout their life Molting – occurs when insects shed their old exoskeletons and replace them with new ones This life cycle is called incomplete metamorphosis Metamorphosis – for insects mean, a change in body form Incomplete Metamorphism: Start as eggs Go through a series of molts Developing stages called nymphs Then reach adulthood Example: grasshopper

16B.3 Insect Life Cycles Complete Metamorphosis Involves 4 stages Egg Larva Most active stage Larvae of moths and butterflies known as caterpillars Known for destructive appetites Other larvae – maggots (flies) and grubs (beetles) Pupa Resting stage where larvae uses food to change body shape Cocoon (moth), chrysalis (butterfly), puparium (flies)

16B.3 Insect Life Cycles Each time one that undergoes COMPLETE metamorphosis and molts, it passes into another stage Most butterflies die soon after it has mated Butterflies do not become bigger butterflies

16B.4 Other interesting Arthropods Not all arthropods are insects Some are barnacles, crabs, lobsters, shrimp, pill bugs, centipedes, scorpions, and tarantulas These differ from insects by the number of body segments and appendages Centipedes and millipedes are not worms Centipedes Flattened One pair of legs per segment Poisonous claws to kill prey Millipedes Somewhat rounded body Can have up to 100 body segments, and most segments will have 2 pairs of legs They are not hunters like centipedes

16B Review 1. What are the three main parts of an insect's body? 2. What type of eyes do insects have? 3. What can we learn from an ant's behavior? 4. List the four stages of metamorphosis 5. List the three arthropods other than insects 6. What sex are worker bees?

16C Echinoderms

16C Echinoderms Starfish – aka sea stars – are ocean dwelling animals that, along with sea urchins, sand dollars, sea cucumbers, and similar organisms are called echinoderms Starfish are supported by a system of hard, flat plates just under the skin Hard plates and spines provide protection Radial symmetry Arms are called rays They can regenerate or grow new rays if needed

16C Echinoderms How do starfish move? Have a water-vascular system that is key to movement Noticeable part of system – rows of tiny tube feet on the bottom of each ray Tube feet function like tiny suction cups They stretch out, attach, and then pull itself forward on hard surfaces Favorite food of starfish – clams Climbs on top of a clam and uses tube feet to pull open shell (could take hours) Then, turns its stomach inside out and pushed it throuh the opening of the clam shell Digestive juices digest the soft part of the clam

16C Review 1. What is the function of the hard plates and spines in a starfish? 2. Where are a starfish's tube feet located? 3. What does a starfish not need teeth?