Chapter 44: Animal Diversity

________________ and _____________ were the first animals to colonize the land, sometime after 420 million years ago.

Chelicerates; insects

A phylum characterized by radial symmetry, two germ tissues in the embryo, a closed internal gastric cavity, and well-developed tissues but not organs; includes jellyfish, sea anemones, and corals:

Cnidaria

____________ form true tissues, differentiate nerve and musclelike cells, and act as predators by means of specialized cells called nematocysts.

Cnidarians

_________________ provided additional information on animal phylogeny, and, in the age of molecular biology, ______________________ have provided still more information.

Embryology; molecular sequence comparisons

________________ are covered with hair and feed their young milk from mammary glands.

Mammals

________________ originated at least 210 million years ago, but became dominant only after the extinction of the ___________________ 65 million years ago.

Mammals; nonavian dinosaurs

Bony fish that have a cranium, jaws, and mineralized bones; there are about 20,000-25,000 species:

Osteichthyes

A gelatinous mass that lies between the interior and exterior cell layers of a sponge that contains some amoeba-like cells that function in skeleton formation and the dispersal of nutrients:

mesohyl

The process in some animals in which the body changes dramatically at key stages in development:

metamorphosis

A type of cell that lines the interior surface of a sponge; have flagella and function in nutrition and gas exchange:

choanocyte

One of the four main groups of arthropods, including lobsters, shrimp, and crabs; distinguished by two pairs of antennae and their branched legs or other appendages:

crustaceans

A nerve cord that develops in a location farther back than the notochord; this embryonic feature is unique to chordates:

dorsal nerve cord

Well-known _________________ are sea stars and sea urchins, which have outward fivefold symmetry.

echinoderms

the inner lining of the cnidarian body:

endodermis

the outer layer of the cnidarian body:

epidermis

In cnidarians, a closed internal site where extracellular digestion and excretion take place:

gastric cavity

In cnidarians, the mouth of both the medusa and polyp form opens into an internal _____ where _____ digestion takes place

gastric cavity; extracellular

A group of mollusks consisting of snails and slugs:

gastropods

Mollusks include ______________ (snails, slugs), _____________ (squid, octopuses), and ______________________ (clams, oysters).

gastropods; cephalopods; bivalve mollusks

The most diverse of the four main groups of arthropods:

insects

Species of fish with paired pectoral and pelvic fins that have a bone structure similar to that of tetrapod limbs; include the coelacanth and lungfish:

lobe-finned fish

In cnidarians, a gelatinous mass enclosed by the epidermis and endodermis:

mesoglea

The series of hard bony segments making up the jointed skeleton that runs along the main axis of the body in vertebrates:

vertebrae

A skeletal structure in vertebrates that functionally replaces the embryonic notochord that supports the body:

vertebral column

A subphylum of Chordata, distinguished by a bony cranium that protects the brain and (unless lost through evolution), a vertebral column; also known as craniates:

vertebrates

Correctly match each group of mollusks with the descriptions below. The mollusk groups may be used once, more than once or not at all. a.gastropods b.cephalopods c.bivalves 1. snails and slugs 2. obtain food by filtering particles from seawater using siphons 3. are able to learn visual patterns and solve puzzles 4. most of the 80,000 described species of mollusks fall into this one group

1. a 2. c 3. b 4. a

The group of vertebrate animals that produces amniotic eggs; this group includes lizards, snakes, turtles, and crocodilians:

Amniotes

A monophyletic group of vertebrates, including frogs and salamanders, with an aquatic larval form with gills and an adult terrestrial form that usually has lungs:

Amphibia

________________ have an aquatic larval form and a terrestrial adult form.

Amphibians

________________ include earthworms and leeches, but most species of them live in the oceans.

Annelid worms

A monophyletic group of animals that includes insects and contains more than half of all known animal species; distinguished by their segmented bodies and jointed legs:

Arthropoda

__________________ can be divided into four main groups—insects, chelicerates (spiders, scorpions), myriapods (centipedes, millipedes), and crustaceans (lobsters, shrimp).

Arthropods

The monophyletic group of animals with bilateral symmetry:

Bilateria

A transition period in geologic time during which the body plans characteristic of most bilaterian phyla developed:

Cambrian explosion

The ______________________ was an interval of rapid diversification beginning 541 million years ago, during which time most of the animal body plans we see today first evolved.

Cambrian explosion

The fossil remains of animals with body plans recognizable as arthropods, echinoderms, mollusks, and other bilaterians first appeared during the _____ Period, around _____ million years ago.

Cambrian; 541

Cartilaginous fish, a monophyletic group that includes about 800 species of sharks, rays, and chimaeras:

Chondrichthyes

One of the three major phyla of deuterostomes, this group includes vertebrates and closely related invertebrate animals such as sea squirts:

Chordata

_______________ include vertebrates, cephalochordates, and tunicates.

Chordates

______________, or comb-jellies, resemble cnidarians but move by the beating of cilia, have an anal pore for waste excretion, and have a rudimentary mesoderm germ layer. They remain a difficult limb to locate on the animal tree of life.

Ctenophores

__________________ include three main phyla—Chordata, Hemichordata, and Echinodermata.

Deuterostomes

__________________ include several phyla that molt their cuticle, notably the nematodes and arthropods.

Ecdysozoans

One of the three major phyla of deuterosomes, defined by five-part symmetry; this group includes sea urchins and sea stars:

Echinodermata

_____________________ from 579 million years ago provide evidence of early animals.

Ediacaran fossils

One of the three major phyla of deuterosomes, this group includes acorn worms and pterobranchs:

Hemichordata

The protostomes are divided into two monophyletic groups, the:

Lophotrochozoa and Ecdysozoa

_______________________ consist of 17 phyla, including annelid worms and mollusks.

Lophotrochozoans

___________ are the closest relatives of tetrapods, which include amphibians, lizards, turtles, crocodilians, birds, and mammals.

Lungfish

_________________ have repeatedly changed the trajectory of animal evolution during the past 500 million years.

Mass extinctions

_______________ have a very simple organization, but genomic data support the hypothesis that they are the sister group to all other eumetazoans.

Placozoans

________________ are divided into lophotrochozoans and ecdysozoans.

Protostomes

____________ have a simple anatomical organization, feed by drawing water containing dissolved food particles into their interiors, and are widespread in the oceans.

Sponges

A monophyletic group of animals whose last common ancestor had four limbs; this group includes amphibians, lizards, turtles, crocodilians, birds, and mammals (some, like snakes, have lost their legs in the course of evolution)

Tetrapoda

__________________ first appear in the fossil record about 360 million years ago.

Tetrapods

Birds are one of two groups of flying vertebrates (bats are the other). Their adaptations for flight include:

a method of breathing that extracts a majority of the oxygen from each breath of air; hollow bones

Vertebrates are distinguished from other chordates by:

a protective cranium in all vertebrates; well-developed vertebrae in all vertebrates

Amniotes, such as lizards, snakes, crocodiles, birds, and mammals, have an _______________, permitting movement into dry, terrestrial habitats.

amniotic egg

An egg that can exchange gases while retaining water, permitting amniotes to reproduce in dry terrestrial habitats that amphibian eggs cannot tolerate:

amniotic egg

A phylum of worms that have a cylindrical body with distinct segments and a bilaterian body plan

annelid worms

A group of mollusks that includes clams, oysters, and mussels; they have an enclosing skeleton in which two hard shells are connected by a flexible hinge:

bivalves

A subphylum of Chordata that shares key features of body organization with vertebrates but lacks a well-developed brain and eyes, has no lateral appendages, and does not have a mineralized skeleton:

cephalochordates

A monophyletic group of mollusks, including squid, cuttlefish, octopus, and chambered nautilus, with distinctive adaptations such as well-developed eyes and muscular tentacles that capture prey and sense the environment.

cephalopods

One of the four main groups of arthropods, including spiders and scorpions, chelicerates have pincer-like claws and are the only arthropods that lack antennae:

chelicerates

A genus of two species of lobe-finned fish found off the coast of Africa and thought to have been extinct for 80 million years but which is still living today:

coelacanth; 1/2 of closest relatives to tetrapods

A body cavity surrounding the gut:

coelom

A bilaterian in which the blastopore, the first opening to the internal cavity of the developing embryo, becomes the anus.

deuterostome

The fossil record is testament to extinct fauna no longer present on Earth. Certain areas of the planet have always had high species diversity (evidence from fossils and catalogs of current species diversity). Which of the processes listed below likely contributed to the patterns of animal diversity we see?

extinction events (both local and global)

One of the earliest-branching craniates, with a cranium built of cartilage but no jaws; feed on marine worms and dead and dying sea animals:

hagfish

The group commonly known as "fish" consists of four distinct groups of aquatic vertebrates: _____________, ________________, __________________, and ______________.

hagfish and lampreys; cartilaginous fish; bony fish; lobe-finned fish.

One of the earliest-branching craniates, with a cranium and vertebral column built of cartilage but no jaws; many live parasitically, sucking body fluids from fish prey:

lamprey

Several species of lobe-finned fish that use a simple lung to survive periods when their watery habitat dries by burying themselves in moist mud and breathing air:

lungfish; 2/2 of closest relatives to tetrapods

A class of vertebrates distinguished by body hair and mammary glands from which they feed their young:

mammals

A group of mammals that includes kangaroos, koalas, and opossums; their young are born at an early stage of development and must crawl to a pouch where mammary glands equipped with nipples provide them with milk:

marsupials

A monophyletic group distinguished by a mantle, which plays a major role in movement, skeleton-building, breathing, and excretion; includes clams, snails, and squid:

mollusks

In chordates, any one of a series of segments that organizes the body musculature:

myotome

One of the four main groups of arthropods, including centipedes and millipedes; distinguished by their many pairs of legs:

myriapods

Roundworms, the most numerous of all animals; a phylum of the Ecdysozoa:

nematodes

In chordates, a cylinder of embryological tissue that develops into a dorsal nerve cord:

neural tube

In chordates, a stiff rod of collagen and other proteins that runs along the back and provides support for the axis of the body:

notochord

A vertical opening separated from other slits by stiff rods of protein in the pharynx of hemichordates:

pharyngeal slit

in hemichordates, a tube that connects the mouth and the digestive tract:

pharynx

an organ formed by the fusion of the chorion and allantois that allows the embryo to obtain nutrients directly from the mother:

placenta

Possibly the simplest of all animals; each contains only a few thousand cells arranged into upper and lower epithelia that sandwich an interior fluid crisscrossed by a network of multinucleate fiber cells:

placozoans

Animals are distinguished from other groups of eukaryotic organisms in that they:

produce collagen; have embryos that include a gastrula stage; are multicellular heterotrophs lacking cell walls

A bilaterian in which the blastopore, the first opening to the internal cavity of the developing embryo, becomes the mouth:

protostome

The quiescent stage of metamorphosis in insects, during which the body tissues undergo a transformation from larva to an adult:

pupa

The fossil record of _________________ reflects a more general pattern of repeated evolutionary innovation and mass extinction.

reef ecosystems

An opening in the exoskeleton on either side of an insect's abdomen through which gases are exchanged:

spiracle

The evolutionary relationships among ___________, ________________, and _________________ remain a subject of research.

sponges; placozoans; ctenophores

Early biologists grouped animals on the basis of shared features of adult bodies, such as ______________ and type of __________________.

symmetry; body cavity

An internal system of tubes in insects that branch from openings along the abdominal surface into smaller airways, directing oxygen to and removing carbon dioxide from respiring tissues:

tracheae

A subphylum of Chordata that includes about 3000 species of filter-feeding marine animals, such as sea squirts and salps

tunicates

Small projections of the water vascular system that extend outward from the body surface and facilitate locomotion, sensory perception, food capture, and gas exchange in echinoderms:

tube feet

A series of fluid-filled canals that permit bulk transport of oxygen and nutrients in echinoderms:

water vascular system