Chapter 18 Flashcards Preview

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Flashcards in Chapter 18 Deck (66):
1

Ingstion

A characteristic that all animals have. Eating food.

2

blastula

A hollow ball of cells.

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gastrula

When the blastula folds inward

4

endoderm

The internal sac formed by gastrulation

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ectoderm

An outer cell layer that gives rise to the outer covering of the animal and, in some phyla, to the central nervous system.

6

mesoderm

A third embryonic cell layer which forms the muscles and most internal organs

7

larva

An immature individual that looks different from the adult animal

8

metamorphosis

A major change of body form that the larva undergoes in becoming an adult capable of reproducing sexually

9

invertebrates

Those animals that lack a vertebral column

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radial symmetry

A body plan where the body parts radiate fro the center like the spokes of a bicycle wheel.

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bilateral symmetry

A body plan that has a mirror-image right and left sides

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anterior

part of bilateral symmetry that is the head end

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posterior

part of bilateral symmetry that is the tail end

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dorsal

part of bilateral symmetry that has a back end

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ventral

part of bilateral symmetry that is the bottom end

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body cavity

Fluid-filled space between the digestive tract and outer body wall that cushions the internal organs and enables them to grow and move independently of the body wall.

17

hydrostatic skeleton

Provides a rigid structure against which muscles contract, moving the animal

18

true coelem

A body cavity completely lined by tissue derived from mesoderm

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pseudocoelem

A body cavity not completely lined by tissue derived from mesoderm

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protostomes

The first opening becomes the mouth

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deuterostomes

The first opening becomes the anus, and the second opening forms the mouth

22

eumetazoans

The animals with true tissues. Every phyla except porifera.

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bilaterians

Those phyla of animals that have bilateral symmetry

24

choanocytes

Inner flagellated "collar" cells of a sponge which help to sweep water through the sponge's body.

25

amoebocytes

One of the layers of the sponge which produce supportive skeletal fibers composed of spongin and spicules

26

suspension feeders, filter feeder

Animals that collect food particles from water passed through some type of food-trapping equipment.

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sessile

Anchored in place

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polyp

A body form of cnidarians that has a cylindrical body with tentacles projecting from one end that is mostly stationary

29

medusa

A freely moving body form of cnidarians that are shaped like an umbrella with a fringe of tentacles around the lower edge

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gastrovascular cavity

A cavity where food is digested. Fluid in the gastrovascular cavity circulates nutrients and oxygen to internal cells and removes metabolic wastes.

31

free-living flatworms

A group of flatworms that has a simple brain and move by using cilia

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flukes

A group of flatworms that live as parasites in other animals and have complex lifecycles

33

tapeworms

A group of flatworms that are similar to flukes that inhabit the digestive tracts of vertebrates

34

cuticle

Several layers of tough nonliving material that cover the body and prevent an organism from drying out.

35

complete digestive tract

A digestive tract where food travels only one way through the system and is processed as it moves along.

36

foot

A part in molluscs that functions in locomotion

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visceral mass

A part in molluscs that contains most of the internal organs

38

mantle

A fold of tissue in molluscs that drapes over the visceral mass and secretes a shell

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radula

A rasping organ in molluscs that is used to scrape up food.

40

circulatory system

An organ system that pumps blood and distributes nutrients and oxygen throughout the body.

41

gastropods

A type of mollusc, includes the only type that can be found on land.

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bivalves

Molluscs that have shells divided into two halves that are hinged together.

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cephalopods

Molluscs that are adapted to the lifestyle of fast, agile predators.

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Segmentation

The subdivision of the body along its length into a series of repeated parts

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open circulatory system

Blood is pumped through vessels that open into body cavities, where organs are bathed directly in blood.

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closed circulatory system

Blood remains enclosed in vessels as it distributes nutrients and oxygen throughout the body. Only annelids and vertebrates have a closed circulatory system.

47

polychaetes

Annelids that are mostly marine. Many are tube-dwellers and extend feathery appendages to feed.

48

leeches

Annelids that are carnivores. Some suck blood.

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arthropods

Invertebrates with segmented, hard exoskeletons, and joint appendages

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exoskeleton

An external skeleton that protects the animal and provides points of attachment for the muscles that move the appendages

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molting

The process of periodically shedding an old exoskeleton and secreting a larger one

52

horseshoe crab

An arthropod that has survived with little change for hundreds of millions of years

53

chelicerates

An ancient group of arthropods that were abundant in the sea some 300 million years ago. Horseshoe crabs are part of this group.

54

arachnids

A group of chelicerates that includes scorpions, spiders, ticks, and mites

55

millipedes

Wormlike terrestrial creatures that eat decaying plan matter. They have two pairs of short legs per body segment.

56

centipedes

Terrestrial carnivores with a pair of poison claws used in defense and to paralyze prey such as cockroaches and flies. Each of their body segments bears a single pair of long legs.

57

crustaceans

A group of arthropods that includes lobsters, crayfish, barnacles, crabs, and shrimp

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complete metamorphosis

The transition from larva to adult involves a pupa stage.

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incomplete metamorphosis

The transition from larva to adult involves multiple molts, but no pupa stage.

60

endoskeleton

An internal skeleton in echinoderms

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water vascular system

A network of water-filled canals in echinoderms that branch into extensions called tube feet.

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notochord

A characteristic in vertebrates that is a flexible, supportive, longitudinal rod located between the digestive tract and the nerve cord

63

pharyngeal slits

A characteristic in vertebrates that is located in the pharynx, the region just behind the mouth.

64

post-anal tail

A tail posterior to the anus

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lancelets

A group of marine invertebrate chordates that feed on suspended particles

66

tunicates

One of two groups that has no notochord in adults but all four chordate features in larvae.