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, insects, humans)

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 Man-

of-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, umbrella-shaped 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 reproduce

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 bristle-

like 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