Chapter 4 (Animal Diversity) FOR EXAM

Collagen

All phyla of the animal kingdom, including sponges, possess _, a triple helix of protein that binds cells into tissues. Not found among unicellular eukaryotes

Presence of collagen

one of the indications that animals arose once from a common unicellular ancestor

Mobilitity

_ constrains an animal to maintain more or less the same shape throughout its active life.

Gastrula

double-walled stage of the embryo resulting from invagination of the blastula; the outer layer of cells is the ectoderm and the inner layer differentiates into the mesoderm and endoderm

coelenterate

radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures

bilateria

consists of multicellular animals with bilateral body symmetry and contain three body layers (triploblastic) with coalition of tissues into organs

Acoelomate

Body plans:
any animal without a body cavity; have no internal fluid-filled body cavity (coelom); ex. flatworms

coelom

the body cavity in metazoans, located between the intestinal canal and the body wall

Pseudocoelomates

Body plans:
_ have a cavity between the inner (endoderm) and the middle (mesoderm) body layers

Coelomates

have a body cavity called a coelom with a complete lining called peritoneum derived from mesoderm (one of the three primary tissue layers);

Schizocoelous

Two types of devopment showed in coelomates:
mesoderm proliferates from a single cell and divides to form a mass on each side of the body; process by which some animal embryos develop

Enterocoelic

Two types of devopment showed in coelomates:
endoderm evaginates and pinches off discrete pouches, the cavities of which become the coelom and the wall the mesoderm; process by which some animal embryos develop and the origin of the cells involved.

Parazoa

two phyla in this subkingdom, Porifera (sponges) and Placozoa, lack clearly defined tissues and organs

Radiata

major grouping that includes more or less radially symmetrical animals

Incipient tissues

groups of cells that are integrally coordinated in the performance of a certain function

endoderm

one of the germ layers, aggregates of cells that organize early during embryonic life and from which all organs and tissues develop

ectoderm

the outer germ layer that develops into skin and nervous tissue; one of the three primary germ layers formed in early embryonic development

Flatworms

_ are considered to be the ancestors of all other Bilateria

Hydrostatic skeletons

most prevalent skeletal system used by animals for movement and support; important in nonlocomotory muscular systems, such as hearts or intestines, which move blood or food; less efficient when fluid is lost

Contraction-relaxation cycles

_ push in one direction only when the system has structures that prevent backflow

Jointed skeletons

ideal for moving on land because adaptations for protection against dehydration (such as the cuticle) do not interfere with the action of the skeletal system; used directly for feeding (jaws).

Locomotion

the power or ability to move; serves the animal in finding food and mates and in escaping predators or unsuitable habitats

Sitting still and waiting for food

Strategies for finding or gathering food techniques:
_ to arrive is particularly
prevalent in aquatic habitats but is not rare on land

Burrowing animals

Strategies for finding or gathering food techniques:
_ typically eat the rich organic substrates they move through

Active movement

Strategies for finding or gathering food techniques:
_ in search of food requires energy, but this expenditure is more than made up for by an ability to seek out areas of concentrated food

Cooperation of individuals

Strategies for finding or gathering food techniques:
_ enables social animals to obtain food in novel ways

Metamerism

the partitioning of the coelom, is thought to have evolved in ancestral annelids to improve their ability as burrowers in the bottom mud of the ocean.

Elastic Skeletons

do not change shape but simply bend when a muscle contracts; ex. The tentacles of many hydrozoan coelenterates, the mesoglea of jellyfish, the hinge of clamshells, and the notochord of chordates

Rigid, jointed skeletons

_ achieve movement through a lever system; Important to the speed and force of a movement are the length of the skeletal element and the size of the contracting muscle with thick muscles (Short limbs have more power than long limbs with slender muscles, but the latter have more speed)

Chemoreceptors

electrical changes are induced by chemicals; usually little-modified sensory neurons, frequently replaced cells in synaptic contact with permanent sensory neurons

Chemoreception

process by which organisms respond to chemical stimuli in their environments that depends primarily on the senses of taste and smell. Common to animals

Sound Receptors

sensitive hair cells or membranes that depolarize a sensory neuron when bent by the passage of a sound wave

Sound

_ is the preferred medium of communication between animals that hear. It can be used over longer distances than vision, and it can be used when vision is not possible

Mechanoreceptors

_ respond to touch, pressure, stretching, and gravity. They are located all over the body and enable an animal to monitor its state at any moment.

Closed circulatory systems

Have a heart with a few vessels leading from it that both leak fluid (which is reclaimed by the open lymphatic system) and have open sections; another advantage is that it has the ability to carry a high density of oxygen-bearing cells.

Fear

_ changes the distribution of blood flow to ready the muscles for possible imminent action

Competition and predation

two major components of any habitat, have complicated the lives of animals, leading to ever more novel ways of surviving

Phylum Porifera

Animal Groups:
Sessile (fixed in one place); vary in form from amorphously matted to delicately sculptured; distinctive flagellated collar cells pump water and extract food; models of efficient flow design; 2 cell layers with gelatinous mesenchyme containing various types of cells, including those producing supporting spicules; colonoid; marine and some freshwater species; filter feeders; Cambrian to recent; 9,000 species.

Phylum Placozoa

Animal Groups:
Flattened, 2 flagellated cell layers; fluid mesenchyme with a few cells and connecting fibers; similar to the larvae of primitive animals, from which they may be derived; digestive method unknown; shape irregular and changing; marine; predators or scavengers; recent; 1 species.

Phylum Cnidaria

Animal Groups:
Possess tentacles with stinging cells (nematocysts) for paralyzing prey or repelling predators; sessile (polyp) and floating (medusa) forms; many have both stages alternating in complex life cycles; medusae with well-developed mesoglea used as elastic skeleton for jet propulsion; muscle cells epithelial; solitary to the most complex of animal colonoids; marine and freshwater species; predators or scavengers with some filterfeeding species; Ediacaran to recent; 9,000 species.

Phylum Ctenophora

Animal Groups:
(comb jellies);Long tentacles of most have sticky lasso cells (colloblasts) to secure prey; comb plates of fused cilia (ctenes) used for swimming; separate muscle cells; marine; predators; Devonian to recent; 100 species.

Phylum Platyhelminthes

Animal Groups:
(flatworms); Lack anus except perhaps in the class Gnathostomulida; no circulatory system; mouth ventral; mesoderm of loose cells (parenchyma); marine and freshwater species, with some terrestrial species known; predators or scavengers, with some parasitic species known; recent; 20,000 species

Phylum Mesozoa

Animal Groups:
Among simplest animals; only organ the gonad; 2 classes probably arose separately; dicyemids with unique within-cell embryo formation; marine; parasitic; recent; 100 species.

Phylum Nematoda

Animal Groups:
(roundworms); Found almost everywhere animals exist; thick, complex cuticle permits high pressure on internal fluid and acts as elastic skeleton; only longitudinal muscles; many internal structures reflect high internal pressure; unique type of excretory organ; some have jaws; marine, freshwater, and terrestrial species; predators or scavengers or parasites; Carboniferous to recent; 12,000 species.

Phylum Annelida

Animal Groups:
Segmented worms; paired appendages or setae on segments used in locomotion; protonephridia or metanephridia; closed circulatory system; some with jaws; some sedentary or sessile; some secrete tubes around them; marine, freshwater, and terrestrial; predators, scavengers, or filter feeders, with some parasitic species known; Cambrian to recent; 15,000 species.