BIO 110: Chapter 10 Biodiversity

Bilateral Symmetry

An arrangement of body parts such that an organism can be divided equally by a single cut passing longitudinally through it. A organism has mirror-image right and left sides.

Heterotrophs

An organism that cannot make its own organic food molecules from inorganic ingredients and must obtain them by consuming other organisms or their organic products; a consumer or a decomposer in a food chain.

Phyla

The taxonomic category that is more narrow than kingdom but more broad than class. Members all have a similar general body plan.

Radial Symmetry

An arrangement of the body parts of an organism like pieces of a pie around an imaginary central axis. Any slice passing longitudinally through a organism’s central axis divides the organism into mirror-image halves.

Cnidarians

An animal characterized by cnidocytes, radial symmetry, a gastrovascular cavity, and a polyp or medusa body form. Include hydras, jellies, sea anemones, and corals.

Invertebrates

An animal that does not have a backbone.

Medusa

One of two types of cnidarian body forms; a floating, umbrella-like body form; also called a jelly.

Polyp

One of two types of cnidarian body forms; a stationary (sedentary), columnar, hydra-like body.

Sponges

An aquatic stationary animal characterized by a highly porous body, choanocytes, and no true tissues.

Annelids

A segmented worm. Include earthworms, polychaetes, and leeches.

Flatworms

A bilateral animal with a thin, flat body form, a gastrovascular cavity with a single opening, and no body cavity. Include planarians, flukes, and tapeworms.

Gastrovascular Cavity

A digestive compartment with a single opening that serves as both the entrance for food and the exit for undigested wastes; may also function in circulation, body support, and gas exchange. Jellies and hydras are examples of animals with this.

Nematodes

An animal characterized by a pseudocoelom, a cylindrical, wormlike body form, and a complete digestive tract; also called a roundworm.

Segmentation

Subdivision along the length of an animal body into a series of repeated parts called segments; allows for greater flexibility and mobility.

Bivalves

Member of a group of mollusks that includes clams, mussels, scallops, and oysters.

Cephalopods

Member of a group of mollusks that includes squids and octopuses.

Foot

In an invertebrate animal, a structure used for locomotion or attachment, such as the muscular organ extending from the ventral side of a mollusk.

Gastropods

(snails and slugs), bivalves (clams, oysters, and scallops), and cephalopods (squids and octopuses).

Mollusks

A soft-bodied animal characterized by a muscular foot, mantle, mantle cavity, and radula.

Radula

A file-like organ found in many mollusks used to scrape up or shred food.

Visceral Mass

One of the three main parts of a mollusk containing most of the internal organs.

Arachnids

Member of a major arthropod group that includes spiders, scorpions, ticks, and mites.

Arthropods

Member of the most diverse phylum in the animal kingdom; includes the horseshoe crab, arachnids (for example, spiders, ticks, scorpions, and mites), crustaceans (for example, crayfish, lobsters, crabs, and barnacles), millipedes, centipedes, and insects. They are characterized by a chitinous exoskeleton, molting, jointed appendages, and a body formed of distinct groups of segments.

Crustaceans

Member of a major arthropod group that includes lobsters, crayfish, crabs, shrimps, and barnacles.

Echinoderms

Member of a group of slow-moving or stationary marine animals characterized by a rough or spiny skin, a water vascular system, typically an endoskeleton, and radial symmetry in adults. Includes sea stars, sea urchins, and sand dollars.

Tube Feet

On the body of an echinoderm, extensions with suction cups that are used to move and to grasp prey.

Chordates

An animal that at some point during its development has a dorsal, hollow nerve cord, a notochord, pharyngeal slits, and a post-anal tail. Includes lancelets, tunicates, and vertebrates.

Endoskeleton

A hard interior skeleton located within the soft tissues of an animal; found in all vertebrates and a few invertebrates (such as echinoderms).

Nerve Cord

An elongated bundle of neurons, usually extending longitudinally from the brain or anterior ganglia. One or more of these and the brain make up the central nervous system in many animals.

Notochord

A flexible, cartilage-like, longitudinal rod located between the digestive tract and nerve cord in chordate animals, present only in embryos in many species.

Pharyngeal Slits

A gill structure in the pharynx, found in chordate embryos and some adult chordates.

Tail

(1) Extra nucleotides added at the end of an RNA transcript in the nucleus of a eukaryotic cell. (2) In a sperm cell, an extension that allows the movement of the sperm. (3) One of four identifying structural features of a chordate.

Vertebrates

A chordate animal with a backbone. Includes lampreys, cartilaginous fishes, bony fishes, amphibians, reptiles (including birds), and mammals.

Bony Fishes

A fish that has a stiff skeleton reinforced by calcium salts.

Cartilaginous Fishes

A fish that has a flexible skeleton made of cartilage.

Gills

An extension of the body surface of an aquatic animal, specialized for gas exchange and/or suspension feeding.

Lobe-Finned Fishes

A bony fish with strong, muscular fins supported by bones.

Operculum

A protective flap on each side of a bony fish’s head that covers a chamber housing the gills.

Swim Bladder

A gas-filled internal sac that helps bony fishes maintain buoyancy.

Amniotic Egg

A shelled egg in which an embryo develops within a fluid-filled amniotic sac and is nourished by yolk. Produced by reptiles (including birds) and egg-laying mammals, it enables them to complete their life cycles on dry land.

Amphibians

Member of a class of vertebrate animals that includes frogs and salamanders.

Reptiles

Member of the clade of amniotes that includes snakes, lizards, turtles, crocodiles, alligators, birds, and a number of extinct groups (most of the dinosaurs).

Tetrapods

A vertebrate with four limbs. Include mammals, amphibians, and reptiles (including birds).

Endotherms

An animal that derives most of its body heat from its own metabolism.

Eutherian

Mammal whose young complete their embryonic development in the uterus, nourished via the mother’s blood vessels in the placenta; also called a placental mammal.

Mammals

Member of a class of endothermic amniotes that possesses mammary glands and hair.

Mammary Glands

A characteristic gland of mammals that secretes milk to nourish the young

Marsupial

A pouched mammal, such as a kangaroo, opossum, or koala. They give birth to embryonic offspring that complete development while housed in a pouch and attached to nipples on the mother’s abdomen.

Monotremes

An egg-laying mammal, such as the duck-billed platypus.

Hominins

Any anthropoid on the human branch of the evolutionary tree, more closely related to humans than to chimpanzees.

Primates

Member of the mammalian group that includes lorises, pottos, lemurs, tarsiers, monkeys, apes, and humans.