Unit 3 Chapter 12 Invertebrates (6 classes) 12.1 Most Animals are invertebrates (ex:sponges) 12.2 Cnidarians and Worms 12.3 Mollusks and Echinoderms 12.4 Arthropods

12.1 Invertebrates are diverse Invertebrates = Animals without a backbone (spine) or bone tissue Live almost everywhere Most are small (exception = giant squid can be 59 feet, 992 lbs.) There are six groups 1-Sponges 4-Mollusks 2-Cniarians 5-Echinoderms 3-Worms 6-Arthropods

12.1 Sponges Simplest multicellular animal on earth Sessile Organisms (live attached to 1 spot & do not move) Have no tissue; no organs Most live in salt (some in fresh h20) Have flagella to move water Specialized cells that form walls, pores, filter out food and O2, digest food Spicules (needlelike spines needed for shape)

12.1 Sponge Reproduction Sponges reproduce asexually. Buds form alongside the parent or break off and float away. Sponges reproduce sexually Sperm (and sometimes egg) cells are released into the water for fertilization A fertilized egg becomes a larva (an immature form at an early stage) that is different from the parent. They have changed little over time.

12.2 Cnidarians & Worms Cnidarians: live in water Central opening surrounded by tentacles Ex: jellyfish, sea anemones, hydras (fresh water), and corals Worms: live in water, land, inside organisms soft, tube-shaped bodies, distinct head

12.2 Cnidarians Feed on plankton, fish, clams Many are Sessile (attached to 1 place) Have stinging tentacles: fingerlike extensions of their bodies that reach into the water Each stinging cell as a nematocyst or capsule that holds a barbed filament which releases poison into prey

12.2 Cnidarians continued Body made up of flexible layers of tissue organized around a central opening which both takes in food and releases waste. Though sessile, they can move their muscles (bend, extend tentacles, swim, etc.) to catch prey Have a simple nervous system

12.2 Cnidarian Reproduction They need water to reproduce Sexual – Sperm carried to eggs in water Fertilization makes a “larva” Asexual Buds are produced on parent plant Carried away by water

12.2 Jellyfish Life cycle includes several stages Body or form of jelly fish is different for each stage Adult female medusa releases fertilized eggs Free swimming larva settle on bottom Polyp’s form on ocean floor Disks begin to form & later separate Disks mature into a new medusa

12.2 Different body plans Body Plan = shape of an animal’s body Radial symmetry – organized around a central point or mouthlike opening leading into gut (jellyfish) Can capture food from any direction Bilateral symmetry – Both halves are equal & has 1 line of symmetry Moves forward head first; good plan for mobile animals (butterfly, worm, human)

12.2 Worms Worms have simple bodies, but complex body systems: digestive, excretory, nervous, circulatory & muscular systems are found in worms Take in oxygen & water thru skin, dirt thru mouth Reproduce sexually & asexually; no distinct male/female worms; have both reproductive structures Segmented Worms: divided into individual compartments or segments (annelids or “ringed” animal)

12.2 Worms Continued Flatworms – Roundworms – found everywhere Have simplest bodies Some move with cilia Absorb nutrients thru their skin (tapeworm) Roundworms – found everywhere More complex body structure Muscles, nervous & digestive systems Important decomposers on land/water

12.3 Mollusks & Echinoderms Soft bodied Many have protective shell Can live on land, salt water, fresh water 3 groups: bi-valves, gastropods, cephalopods

12.3 Mollusks continued Have well-developed organ systems (muscles, digestive, respiratory, circulatory, and nervous systems) Reproduce sexually with distinct male & female organisms All have a muscular foot to which its head is attached. All have a mantle or layer of folded skin that protects internal organs. Ex: Oysters, clams, snails, mussels, octopi, squids, slugs Snails are gastropods (“belly foot”)

12.3 Bi-Valve Mollusks Have hard shell w/two matching halves When shell closes, body is completely enclosed and protected Body = a mass of tissue; no distinct head, but do have mouth and sensory organs plus gills to filter 02 and food. They are filter feeders Ex: Clams, mussels, scallops and oysters

12.3 Gastropods Most diverse of mollusks Many are protected by spiral shaped shells, live on land (have lungs) or water (have gills) Head located at end of foot. Head has eyes and tentacles for sensing Many have cutting mouths (radula) Some eat animals, but most eat plants/algae Ex: Snails, slugs, conches, whelks, periwinkles

12.3 Echinoderms Live in the ocean Have radial symmetry Bottom feeders w/mouth at center Some are predators (eat clams/snails, etc.) Echinoderm means “spiny skinned.” Skeleton made up of stiff hard plates, but they have no bones Some flexible (sea star); some stiff (sand dollars) Ex: Sea stars, sea urchins, sea cucumbers, & sand dollars

12.3 Echinoderms cont. They have a unique water vascular system – water-filled tubes that radiate out from the center of their body. At the base of these tubes are tube feet. At the top of each tube is a muscle which can close off the tube and create suction. Tubes can then help with movement, or hunting or disabling prey. Examples: Starfish & Sea Urchins

12.4 Arthropods Arthropods = invertebrate (iv) that has a segmented (jointed) body covered with a hard outer skeleton (exoskeleton). Most iv’s are arthropods (more species than any other animal class) ¾ of all animal species are arthropods First appeared on land 420 million years ago (about same time as plants)

12.4 Arthropods - Exo – skeletons & Jointed Parts Most live on land; some in water Ex: Insects, crustaceans = shrimp, arachnid/spider, scorpion) Exoskeleton = strong outer covering made of material called chitin which keeps cells, organs from drying out. Joints = places where exoskeleton is thin and flexible (body, legs, antennae, claws) to which muscles attach for movement Body typically has 3 sections: head, thorax (middle), and abdomen Molting = shedding of exoskeleton for growth; leaves animal vulnerable to prey during molt.

12.4 Complex Body Systems Nervous (brain), digestive (stomach & intestine), circulatory (heart but no blood vessels) They reproduce sexually with distinct male or female reproductive system thorax antennae abdomen head Jointed legs

12.4 Insects = 6 legged 700,000 species. Insect = arthropod that as an adult has 3 body segments (head, thorax, abdomen), 2 antennae, 6 legs attached to thorax (middle). Most live on land; & are everywhere! Obtain O2 through spiracles, small openings in their exoskeletons

12.4 Insects Great diversity in appearance (color, shape, etc) Many have compound eyes and Antennae (sensory organs) Many fly with 1 or 2 pairs of wings Many are herbivores Some are “social” like ants/bees and must live in groups to survive.

12.4 Insects - Reproduce sexually with female laying the eggs (many eggs!) Metamorphosis = “change” - Insects undergo a life cycle process in which their appearance and body systems may change dramatically. Complete metamorphosis has 3 stages: 1.larva 2. pupa 3.adult

12.4 Insects Not all insects go thru complete metamorphosis. Simple metamorphosis: only 2 stages: usually egg to adult form, (but smaller in size). Larval form = caterpillar stage

12.4 Crustaceans Most live in water and some on land. Tiny krill and copepods are important food source in the oceans 3 or more pairs of legs, 2 pairs of sensory antennae Some have gills; most have circulatory system but no blood vessels Reproduce sexually from eggs Some are herbivores, some carnivores; many are scavengers

12.4 Crustaceans Can be sessile (barnacles) or mobile Crustaceans include: shrimp, lobster, crab, barnacles, krill, copepods (ocean) pill bugs (land)

12.4 Arachnids = 8 legged Includes spiders, mites, ticks, & scorpions 4 pairs of legs; 2 body parts no antennae Exoskeleton; Jointed Legs

12.4 Arachnids cont. Some are parasites (ticks, chigger mites) Some are predators (spiders, scorpions) and have venom. Spiders are largest group Spiders and silkworms have spinnerets to produce silk Most obtain O2 through spiracles Some spiders have “book lungs” in their abdomen.

12.4 Millipedes and Centipedes Long, segmented bodies & many legs in pairs on each segment. Millipedes … have 2 pairs of legs per segment move slowly & eat decaying plant matter Centipedes … have 1 pair of legs per segment Move quickly & are predators Have antennae and jaws & some have rear pincers