1 Unit 3 Chapter 12 Invertebrates (6 classes) 12.1 Most Animals are invertebrates (ex:sponges)12.2 Cnidarians and Worms12.3 Mollusks and Echinoderms12.4 Arthropods
2 12.1 Invertebrates are diverse Invertebrates = Animals without a backbone (spine) or bone tissueLive almost everywhereMost are small (exception = giant squid can be 59 feet, 992 lbs.)There are six groups1-Sponges 4-Mollusks2-Cniarians 5-Echinoderms3-Worms 6-Arthropods
3 12.1 Sponges Simplest multicellular animal on earth Sessile Organisms (live attached to 1 spot & do not move)Have no tissue; no organsMost live in salt (some in fresh h20)Have flagella to move waterSpecialized cells that form walls, pores, filter out food and O2, digest foodSpicules (needlelike spines needed for shape)
4 12.1 Sponge Reproduction Sponges reproduce asexually. Buds form alongside the parent or break off and float away.Sponges reproduce sexuallySperm (and sometimes egg) cells are released into the water for fertilizationA fertilized egg becomes a larva (an immature form at an early stage) that is different from the parent.They have changed little over time.
5 12.2 Cnidarians & Worms Cnidarians: live in water Central opening surrounded by tentaclesEx: jellyfish, sea anemones, hydras (fresh water), and coralsWorms: live in water, land, inside organismssoft, tube-shaped bodies, distinct head
6 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 waterEach stinging cell as a nematocyst or capsule that holds a barbed filament which releases poison into prey
7 12.2 Cnidarians continuedBody 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 preyHave a simple nervous system
8 12.2 Cnidarian Reproduction They need water to reproduceSexual –Sperm carried to eggs in waterFertilization makes a “larva”AsexualBuds are produced on parent plantCarried away by water
9 12.2 Jellyfish Life cycle includes several stages Body or form of jelly fish is different for each stageAdult female medusa releases fertilized eggsFree swimming larva settle on bottomPolyp’s form on ocean floorDisks begin to form & later separateDisks mature into a new medusa
10 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 directionBilateral symmetry – Both halves are equal & has 1 line of symmetryMoves forward head first; good plan for mobile animals (butterfly, worm, human)
11 12.2 WormsWorms have simple bodies, but complex body systems: digestive, excretory, nervous, circulatory & muscular systems are found in wormsTake in oxygen & water thru skin, dirt thru mouthReproduce sexually & asexually; no distinct male/female worms; have both reproductive structuresSegmented Worms: divided into individual compartments or segments (annelids or “ringed” animal)
12 12.2 Worms Continued Flatworms – Roundworms – found everywhere Have simplest bodiesSome move with ciliaAbsorb nutrients thru their skin (tapeworm)Roundworms – found everywhereMore complex body structureMuscles, nervous & digestive systemsImportant decomposers on land/water
13 12.3 Mollusks & Echinoderms Soft bodiedMany have protective shellCan live on land, salt water, fresh water3 groups: bi-valves, gastropods, cephalopods
14 12.3 Mollusks continuedHave well-developed organ systems (muscles, digestive, respiratory, circulatory, and nervous systems)Reproduce sexually with distinct male & female organismsAll 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, slugsSnails are gastropods (“belly foot”)
15 12.3 Bi-Valve Mollusks Have hard shell w/two matching halves When shell closes, body is completely enclosed and protectedBody = a mass of tissue; no distinct head, but do have mouth and sensory organs plus gills to filter 02 and food.They are filter feedersEx: Clams, mussels, scallops and oysters
16 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 sensingMany have cutting mouths (radula)Some eat animals, but most eat plants/algaeEx: Snails, slugs, conches, whelks, periwinkles
17 12.3 Echinoderms Live in the ocean Have radial symmetry Bottom feeders w/mouth at centerSome are predators (eat clams/snails, etc.)Echinoderm means “spiny skinned.”Skeleton made up of stiff hard plates, but they have no bonesSome flexible (sea star); some stiff (sand dollars)Ex: Sea stars, sea urchins, sea cucumbers, & sand dollars
18 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
19 12.4 ArthropodsArthropods = 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 arthropodsFirst appeared on land 420 million years ago (about same time as plants)
20 12.4 Arthropods - Exo – skeletons & Jointed Parts Most live on land; some in waterEx: 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 movementBody typically has 3 sections: head, thorax (middle), and abdomenMolting = shedding of exoskeleton for growth; leaves animal vulnerable to prey during molt.
21 12.4 Complex Body SystemsNervous (brain), digestive (stomach & intestine), circulatory (heart but no blood vessels)They reproduce sexually with distinct male or female reproductive systemthoraxantennaeabdomenheadJointedlegs
22 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
23 12.4 Insects Great diversity in appearance (color, shape, etc) Many have compound eyes andAntennae (sensory organs)Many fly with 1 or 2 pairs of wingsMany are herbivoresSome are “social” like ants/bees and must live in groups to survive.
24 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 has3 stages: 1.larva 2. pupa 3.adult
25 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
26 12.4 Crustaceans Most live in water and some on land. Tiny krill and copepods are important food source in the oceans3 or more pairs of legs, 2 pairs of sensory antennaeSome have gills; most have circulatory system but no blood vesselsReproduce sexually from eggsSome are herbivores, some carnivores; many are scavengers
27 12.4 Crustaceans Can be sessile (barnacles) or mobile Crustaceans include: shrimp, lobster, crab, barnacles, krill, copepods (ocean)pill bugs (land)
28 12.4 Arachnids = 8 legged Includes spiders, mites, ticks, & scorpions 4 pairs of legs; 2 body partsno antennaeExoskeleton; Jointed Legs
29 12.4 Arachnids cont. Some are parasites (ticks, chigger mites) Some are predators (spiders, scorpions) and have venom.Spiders are largest groupSpiders and silkworms have spinnerets to produce silkMost obtain O2 through spiraclesSome spiders have “book lungs” in their abdomen.
30 12.4 Millipedes and Centipedes Long, segmented bodies & many legs in pairs on each segment.Millipedes …have 2 pairs of legs per segmentmove slowly & eat decaying plant matterCentipedes …have 1 pair of legs per segmentMove quickly & are predatorsHave antennae and jaws & some have rear pincers