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Kingdom Animalia (Invertebrates) Characteristics of Animals • • • • • Multicellular Eukaryotic Heterotrophic consumers Most are motile, but some are sessile Most consist of cells that are organized into tissues and organs • Most reproduce sexually Habitats of Animals • Terrestrial—live on land • Aquatic—live in water – Freshwater—live in water that is not salty (ex. ponds, lakes, streams, rivers) – Marine—live in salt water (ex. oceans) Classification of Animals • Invertebrates—animals without a backbone (95 % of animals) • Vertebrates—animals with a backbone (5 % of animals) Types of Body Symmetry • Asymmetry—have no symmetry (ex. sponges) • Radial Symmetry—has parts arranged around a central axis; any plane passing through the central axis divides the animal into halves that are mirror-images of one another (ex. jellyfish, starfish) • Bilateral Symmetry—the right and left half of the animal are mirror-images of each other; animals with this type of symmetry generally have cephalization, a concentration of nervous tissue in the head region (ex. worms, Anatomical Terminology • • • • • • Dorsal—the back surface of an animal Ventral—the underside of an animal Anterior—the front end of an animal Posterior—the rear end of an animal Lateral—the sides of an animal Medial—along the midline of an animal Primary Animal Phyla • Porifera—sponges • Cnidaria—jellyfish, coral, Portuguese Manof-War, hydra • Platyhelminthes—flatworms (tapeworms, flukes, planarians) • Nematoda—roundworms (pinworms, hookworms) • Annelida—segmented worms (earthworms, leeches) Primary Animal Phyla (continued) • Mollusca—snails, slugs, octopus, squids, clams, oysters • Arthropoda—insects, spiders, scorpions, crayfish, crabs • Echinodermata—starfish • Chordata—fish, frogs, snakes, turtles, lizards, birds, dogs, cats, horses, humans Phylum Porifera • • • • “Pore bearers”, the sponges Have no definite shape or symmetry Have no tissue organization Most are marine, but some are freshwater • Adult sponges are sessile; larvae are free-swimming Phylum Porifera (continued) • The body of a sponge is shaped like a sac; the inside is a hollow cavity • Sponges have a large opening at the top of the cavity called an osculum (no mouth) • The body of a sponge has numerous tiny pores, through which water moves into the animal; the sponge gets its food and oxygen from this water Phylum Porifera (continued) • Sponges are “filter feeders”; as water moves into the sponge through the pores, it is filtered of small particles of food • Collar cells are cells that line the inner body cavity; they have flagella which beat to draw water through the sponge and out the osculum, filtering the water in the process • Spicules are needle-like structures that support the soft material of a sponge Phylum Porifera (continued) • Sponges can reproduce either asexually or sexually • During asexual reproduction, a small growth, or bud, can break off the main part of the sponge, attach to a substrate, and eventually grow into a separate new sponge • During sexual reproduction, specialized cells can develop into either sperm or eggs; the sperm swim out of the osculum and into another sponge; there they fertilize eggs; the larvae swim out of the osculum to become new sponges Phylum Porifera (continued) • Sponges are hermaphroditic, which means that they produce both sperm and eggs • Most have the ability to regenerate; when cells of a sponge are separated from one another (as when they are injured), they can reorganize and form a new sponge Phylum Cnidaria • Animals with stinging cells • Jellyfish, Hydra, Obelia, coral, sea anemone, Portuguese Man-of-War • Most are marine • Have radial symmetry • Have some tissue organization Phylum Cnidaria (continued) • There are two main body forms found in cnidarians: – Polyp—cylindrical, usually sessile animals which have their mouths directed upwards and tentacles surrounding it – Medusa—generally free-floating, umbrellashaped animals which have their mouths directed downwards and tentacles hanging down around it Phylum Cnidaria (continued) • Some cnidarians exist only as polyps; some exist only as medusae; others alternate between the two forms • Some cnidarians exist singly; some exist as colonies of animals • Cnidarians can reproduce asexually (by budding) or sexually (by production of gametes) Phylum Cnidaria (continued) • Cnidarians have stinging cells which are used in capturing prey; when stimulated, the cells poison/paralyze the prey so it can be eaten • The mouth of the animal leads into a cavity where digestion occurs • Wastes are expelled out the mouth Phylum Platyhelminthes • Flatworms (ex. planarians, flukes, and tapeworms) • Have flattened bodies, bilateral symmetry, and cephalization • Have distinct tissue layers • Simplest animals with organs Planarians • Free-living flatworms • Freshwater (found in ponds, lakes, and streams) • Scavengers • Hermaphroditic • Breathe through skin • Regenerate well Planarians (continued) • Mouth—only body opening; located halfway down the body on the ventral surface; can project its pharynx (throat) out the mouth to suck up food • Intestines—digest food • Eyespots—sensory structures used for detecting light; planarians prefer darkness Flukes • Parasitic flatworms (internal parasites); blood flukes and liver flukes can infect humans • Oral suckers enable the worm to attach to the intestines of the host • Hermaphroditic; body primarily consists of reproductive organs Life Cycle of a Fluke • Eggs are released from an infected individual with wastes; in some areas of the world, human wastes are used as fertilizer for crops • Eggs hatch into larvae in swampy, marshy land areas (mainly in Asia and the tropics) • Sometimes snails serve as intermediate hosts • Larvae may enter humans through the skin (of the feet usually) • Larvae then pass through the bloodstream to the intestines, where they attach, feed, and Tapeworms • Parasitic flatworms (internal parasites); beef tapeworms, fish tapeworms, and pork tapeworms can infect humans • The tapeworm’s head has hooks and suckers which enable the worm to attach to the host’s intestine • The body consists of a long chain of segments Tapeworms (continued) • Hermaphroditic; each segment contains reproductive organs • Segments that are farthest from the head contain mature eggs; these are shed daily and released from the body of an infected individual with the feces Life Cycle of a Tapeworm • If a human eats poorly cooked beef, pork, or fish that contains larvae, infection can occur • The cow, pig, or fish (intermediate hosts) can be infected by eating food which contains the tapeworm eggs • Once inside the animal, the eggs become embryos, and then larvae; the larvae encyst in muscle, which is the part eaten by humans • When a human eats the infected meat, digestive juices break down the cysts and release the larvae Life Cycle of a Tapeworm (continued) • The larvae attach to the intestines, where they feed, grow, and reproduce, when mature • Tapeworms may grow up to 50 feet long and may live within a host for up to 10 years • Symptoms of infection include weight loss, increased appetite, and occasionally pain and discomfort Phylum Nematoda • Roundworms (ex. hookworms, pinworms, heartworms) • Found almost everywhere—in soil, freshwater, and saltwater; many are parasites • Have a tube-like body and bilateral symmetry • Distinct tissue layers and definite organs • Usually separate sexes; males are generally smaller in size than females Phylum Nematoda (continued) • Complete digestive tract with a mouth at one end and an anus at the other • Body is covered by a tough cuticle, which is a thickening of the epidermis that protects the worm (from drying out); the cuticle is shed, or molted, as the worm grows • Beneath the epidermis is a layer of muscles that allows the worm to move by thrashing back and forth Hookworms • Internal parasites; live in the human intestine, where they feed, mature, and lay eggs • The eggs pass out of the body with the feces • If human wastes are used as fertilizer, the larvae develop in the soil • They may enter a human through the skin (usually by boring through the skin of the feet as an individual walks on soil contaminated with larvae) • The larvae migrate through the body to the intestine Pinworms • The most common parasitic worms found in children • May enter a human host if the individual ingests eggs by eating with dirty hands • Adult worms are about ½ inch long • They live in the large intestine Pinworms (continued) • Female worms migrate to the host’s anus (usually at night) to deposit eggs • This causes itching, irritation, and scratching, which spreads the eggs • The eggs can even be spread in the air to other people • Some pinworm infections are mild; some cause much intestinal discomfort Phylum Annelida • Segmented worms (ex. earthworms, leeches, sandworms); have many body segments • Found in freshwater, marine, or terrestrial habitats • Have bilateral symmetry Leeches • Live in freshwater, but are also external parasites • May attach to the skin of a host with suckers at each end of the body • Suck blood, which is stored in pouches within their bodies • Secrete an anticoagulant which keeps blood from clotting; leeches are occasionally used in medicine Earthworms • Burrow in the soil using paired bristlelike structures; these structures are found on the ventral surface of each body segment • Earthworms are important ecologically because they aerate the soil as they burrow Earthworms (continued) • Complete digestive tract with a mouth at one end and an anus at the other • Body is covered by a cuticle, which is secreted by the epidermis and helps to prevent the worm from drying out; the epidermis also secretes mucus to further prevent drying out Earthworms (continued) • Body wall consists of an outer layer of circular muscles and an inner layer of longitudinal muscles • Respiration occurs through the skin • Kidney-like structures that excrete liquid wastes located in each body segment Earthworms (continued) • Digestive system is quite advanced; consists of the following structures (in order from anterior to posterior): – – – – – – – Mouth—food (mixed with soil) enters here Pharynx—throat; a passageway Esophagus—a passageway Crop—stores food Gizzard—grinds food Intestine—digests food; a passageway Anus—eliminates wastes Earthworms (continued) • Circulatory system is also quite advanced; consists of the following structures: – 2 main blood vessels, one dorsal and one ventral – 5 pairs of arched blood vessels that connect the other two vessels; these vessels pump blood, so they make up the “heart” Earthworms (continued) • Nervous system consists of: – Ventral nerve cord – Paired masses of tissue called ganglia; this is the “brain” Earthworms (continued) • Hermaphroditic • Reproductive system consists of: – Clitellum—a thickened band of the epidermis that secretes a mucus substance, which is used to hold two worms together during sexual reproduction – Seminal vesicles—produce sperm – Seminal receptacles—receive and store sperm Phylum Mollusca • Soft-bodied animals • Includes snails, slugs, clams, scallops, oysters, octopuses, squids • Many are marine, but some are freshwater, and some are terrestrial • The body of most mollusks is covered by a shell Structure of Mollusks • A muscular foot is used for movement; in the octopus and squid, the foot is divided into tentacles, which are also used for food-getting • The visceral mass contains most of the internal organs • The mantle is a heavy fold of tissue which covers the visceral mass; it contains glands that secrete the shell • Gills are used for respiration in aquatic mollusks Structure of Mollusks (cont.) • Mollusks have a digestive system consisting of a mouth, esophagus, stomach, intestine, and anus • Many have an open circulatory system, which consists of a heart, blood vessels, and blood; in an open system, though, the blood bathes the body tissues directly by pooling in a blood-filled cavity Structure of Mollusks (cont.) • Sexes are usually separate, and fertilization generally takes place in the surrounding water; most marine mollusks pass through one or more larval stages Special Mollusk Features • Bivalve mollusks are filter feeders; they get food particles from the water they draw into their bodies • If a piece of foreign matter lodges between the bivalve’s shell and mantle, a pearl can form • The mantle secretes the shell; the interior of the shell is made of a substance called mother of pearl; this substance surrounds the foreign particle and forms a pearl Special Mollusk Features (cont.) • Cephalopods (octopus and squid) are active, predatory animals that move by jet propulsion; they take in water, and then force it out to push themselves through the water • The octopus has 8 tentacles; the squid has 10 • An octopus has no shell; the squid’s shell is a hard, internal structure called a pen Special Mollusk Features (cont.) • Cephalopods are active at night and in the dark depths of the ocean; they have large, well-developed eyes that can actually see images (much as human eyes) • Many cephalopods can change colors to fool predators; some have ink sacs that release a dark liquid that blinds predators Phylum Arthropoda • The most successful group of animals in terms of number and types of habitats • Animals with jointed appendages (walking legs, swimming structures, claws, antennae, specialized mouthparts) • Includes insects, spiders, crayfish, crabs Characteristics of Arthropods • Exoskeleton—a hard, external skeleton that covers the entire body; provides for muscle attachment, gives support/structure to the body, protects against drying out and predators; periodically shed as the animal grows by a process called molting Characteristics of Arthropods (cont.) • Body segmentation; insects have 3 main body regions; spiders have 2 • Open circulatory system • Nervous system consists of a nerve cord and ganglia (the “brain”) Charcteristics of Arthropods (cont.) • Well-developed sense organs such as antennae and compound eyes • Respiratory system consists of gills in aquatic animals and lung-like structures in terrestrial forms Arachnids • Includes spiders, daddy longlegs, scorpions, ticks, mites, and chiggers (the larval form of a red mite) • Body consists of 2 main body regions • 4 pair of walking legs (8 legs total) • Have fang-like structures used in getting prey • Have appendages used to hold and chew food; most arachnids feed on insects and other arthropods Arachnids (cont.) • Respiration is usually by book lungs • Many spiders have silk glands in their abdomens which secrete a protein substance used in making webs; spinnerets are structures used to spin the substance into webs, which are used for trapping prey and/or as nests • All spiders have poison glands used in capturing food, but only a few produce poisons that are toxic to humans Poisonous Spiders in Our Area • Black Widow—produces a neurotoxin that interferes with nervous system transmission • Brown Recluse—produces a hemotoxin that causes tissues to die Centipedes • “100-legged animals” (they don’t really have that many legs) • Terrestrial; found under rocks or wood • Have a flattened body, a head, an elongated trunk with many segments, and one pair of legs per segment • Carnivorous; feed on insects and other small animals; have poison claws just behind the head • Move rapidly Millipedes • “1000-legged animals” (they also don’t really have that many legs) • Terrestrial; also found under rocks or wood • Have a cylindrical body, a head, an elongated trunk with many segments, and two pair of legs per segment • Herbivorous; feed on living and decomposing plants • Move slowly Crustaceans • Includes lobster, crayfish, shrimp, and crab • Mainly marine, but a few freshwater • Body consists of 2 main body regions • 5 pair of walking legs (10 legs total; 2 are claws) • Have mandibles, or jaws, for biting and grinding food Crustaceans (cont.) • Have 2 pair of sense organs for touch and taste: antennae and antennules • Have large eyes • Have appendages used to hold food • Respiration is with gills • Green glands are excretory organs found in the head Crustaceans (cont.) • Nervous system consists of ganglia and a nerve cord • Sexes usually separate; the male uses specialized appendages to transfer sperm to the female; the eggs hatch into larvae, which go through a series of molts and stages before reaching adulthood Insects • • • • • • • The most successful animals on Earth Most are terrestrial, but some are aquatic Have complex mouthparts Body consists of 3 main body regions 3 pair of legs (6 legs total) Usually have 2 pair of wings Have 1 pair of antennae Insects (cont.) • Have both simple eyes and compound eyes • Respiration is with tracheae, or air tubes • Sexes separate; fertilization is internal Insects (cont.) • Development is called metamorphosis because if consists of a series of stages: – Incomplete metamorphosis • egg nymphadult – Complete metamorphosis • egglarvapupaadult Insects (cont.) • Many insects live in colonies/societies, with each member carrying out a specific function (ex. Bees and ants) • Insects are not all harmful pests (ex. Bees produce honey; other animals feed on insects; some insects decompose dead organisms and wastes) Phylum Echinodermata • Spiny-skinned animals • Includes starfish, sand dollar, sea urchin, brittle star, and sea cucumber • Have bilateral symmetry as larvae; radial symmetry as adults • All are marine Phylum Echinodermata (cont.) • Have an internal skeleton, or endoskeleton • Move by use of a water vascular system, consisting of a network of canals through which water circulates; branches of these canals lead to numerous tube feet, which are used for movement and food-getting • Very little development of the nervous, circulatory, excretory, and respiratory systems; no brain or heart Phylum Echinodermata (cont.) • Digestive system is the most advanced system • Usually separate sexes; sperm and eggs are released into the water, where fertilization occurs • Starfish have an excellent ability to regenerate lost arms