Ch. 34 Animal Diversity

Choanoflagellates

• single celled eukaryotes

• sister to animals

• marine organisms, for simple multicellular groups

Sponges

porifera

• no complex tissues or organs

• irregular form (no symmetry)

• flower vase shape

• symbiotic relationships with bacteria

Choanocytes

cells that line the interior surface of sponges

• have flagella

• function is nutrition and gas exchange

• collar of cilia around flagellum

Mesohyl

gelatinous mass between interior and exterior cells

• mostly non-cellular

• contains amoeba-like cells that function in skeleton formation, reproduction, and dispersal of nutrients

Spicules

simple structures that make up skeleton of sponges

• glass-like, silica, proteins, calcium carbonate

Eumetazoa

where most animal diversity falls within

• cell types, distinct tissues, gastrulation

• digestive system using enzymes in compartment

Cnidaria

form major branch of Eumetazoa

• radial symmetry

• diploblastic

• closed gastric cavity (food enters and exits same opening)

• well-developed tissues, no organs

Bilateria

monophyletic group with bilateral symmetry

Epidermis

outer layer, develops from outer germ layer

Endodermis

inner germ layer

Mesoglea

gelatinous mass that epidermis and endodermis enclose

Ctenophores

resemble cnidarians

• radial symmetry

• flow-through gut

• movement via cilia

• simple nerve net

• anal pore and mouth

Placozoans

simplest of animals

• few thousand cells in upper and lower epithelia

• cilia for movement

• few differentiated cell types

• genes for transcription and signaling

Protostomia

blastopore forms into mouth

• bilaterians

Deuterostomia

blastopore forms into anus

• bilaterians

Lophotrochozoa

bilaterians that includes mollusks and annelid worms

protostome

triploblastic

Ecdysozoa

• protostome animals

• bilateral

• molting of exoskeleton during growth

Lopophore

tentacle-lined organ for filter feeding

Annelid worms

• lophotrochozoans

• cylindrical body

• segmentation

• bilateral

• lophotrochozoans

• mantle for movement

• skeleton-building

• breathing

• excretion

Gastropods

• mollusks

• snails and slugs

• radula for feeding

• gut cavity and anus

• gills for gas exchange

Cephalopods

• mollusks

• eyes

• mantle tissue for jet propulsion

• tentacles for capturing and sensing

Bivalves

• mollusks

• enclosing skeleton made of two mineral shells

• flexible hinge of shells

Nematodes

roundworm

• most numerous of all animals

• ecydosoza

• mouth, anus, intestine, nerv cords

Arthropods

insects, crabs, shrimps

• most diverse animals

• jointed legs

• have chitin in exoskeleton

Chitin

polysaccharide containing N that makes up cell walls of fungi and exoskeletons of arthropods

Insects

• arthropods

• head, thorax, abdomen, 6 walking legs

Chelicerates

• arthropods

• pincer-like claws

• lack antennae

Myriapods

many pairs of legs

• millipedes and centipedes

Crustaceans

• 2 antennae

• branched legs/appendages

Metamorphosis

body changes dramatically at key stages in development

Spiracles

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

Tracheae

in animals with lungs, central airway leading to lungs supported by rings of cartilage

Hemichordata

• deuterostome

• wormlike marine invertebrates

• includes acorn worms and pterobranchs

Echinodermata

• deuterostomes

• 5 part symmetry

• sea urchins and stars

Chordata

• deuterostomes

• includes vertebrates

• sea squirts and lancelets

• notochord at some stage of development

Pharynx

region of throat that connects the mouth and nasal cavities to digestive system (and lungs in vertebrates)

Pharyngeal slits

vertical openings separated by stiff rods of protein

• function in filter feeding

Dorsal nerve cord

nerve cord that develops in location dorsal to the notochord

• unique to chordates

Water vascular system

fluid-filled canals that permits bulk transport of oxygen and nutrients in echinoderms

Tube feet

small projections of the water vascular system that extend outward from the body surface

• allow echinoderms to crawl, sense environment, capture food, and breathe

Cephalochordates

• chordata

• lack well developed brain and eyes

• no lateral appendages

• no mineralized skeleton

Tunicates

• chordata

• filter-feeding marine animals

Vertebrates

aka craniates

• chordata

• bony cranium that protects brain and vertebral column

Notochord

stiff rod of collagen and proteins that runs along back

• provides resistance for muscles

• later replaced by vertebral column in vertebrates

Vertebral column

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

Neural tube

cylinder of embryological tissue that develops into a dorsal nerve cord

• in chordates

Myotomes

any one of a series of segments that organizes the body musculature

Vertebrae

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

Hagfish

vertebrate animal with cranium built of cartilage but no jaws

Lampreys

vertebrate animal with a cranium and vertebral column built of cartilage but no jaw

• live parasitically (sucking body fluids from fish prey)

Cartilaginous fishes

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

• also known as chondrichthyes

Bony fishes

fish that have a cranium, jaws, and mineralized bones

Lobe-finned fishes

species of fish with paired pectoral and pelvic fins that have a bone structure similar to that of tetrapod limbs

Coelacanth

species of lobe-finned fish thought to have been extinct but that still live today

Lungfish

closest relatives of tetrapods

• use a simple lung to survive periods when watery habitat dries by burying themselves in moist mud and breathing air

Tetrapods

have 4 limbs

• some tetrapods lost their legs in evolution (snakes)

Amphibians

group of vertebrates

• aquatic larval form with gills

• adult terrestrial from that usually has lungs

Amniotic egg

egg that can exchange gases while retaining water, permitting reproduction in dry terrestrial habitats

Amniotes

group of vertebrate animals that produces amniotic eggs

Mammals

vertebrates covered in body hair and mammary glands from which they feed their young

Marsupials

young are born at an early stage of development, must crawl to abdominal mammary glands that provide them with milk

Placental mammals

a mammal that provides nutrition to the embryo through the placenta

• placenta is a temporary organ that develops in the uterus