BIOS 1620 Chapter 33 The Invertebrates

invertebrates

animals without a backbone (95% of all animal species)

spongocoel

central cavity of a sponge

choanocytes

collar cells that beat to move water through pores and sponge; trap and eat small particulates and plankton

mesohyl

gelatinous, protein-rich matrix between choanocytes and epithelial cells

amoebocytes

mobile cells within the mesohyl that absorb food from choanocytes, digest, and carry the nutrients to other cells

sponges

unique in their use of intracellular digestion (uptake of food particles by cells)

spicules

tough, sharp skeletal fibers that support the body forming skeleton; formed of protein, calcium carbonate, or silica

spongin

fibers of tough protein that lend skeletal support (skeleton sold as bath sponges)

hermaphrodites

produce both sperm and eggs

mesoglea

gelatinous substance connecting endoderm and ectoderm

gastrovascular cavity

body cavity with a single opening to the external environment where extracellular digestion takes place

nerve net

true nerve cells in Radiata consisting of interconnected neurons with no central control organ; nerve impulses pass in either direction along a neuron

polyp

sessile form of cnidarians; tubular body with an opening at the oral end that is surrounded by tentacles and functions as both mouth and anus, bottom end is attached to substrate

medusa

motile form of cnidarians; has an umbrella-shaped body with an opening that serves as both mouth and anus on the concave underside that is surrounded by tentacles, often possess simple sense organs

ocelli

photosensitive organs; allow medusa to position themselves in particular light levels

cnidocytes

stinging cells, function in defense or capture of prey

nematocysts

powerful capsules with an inverted coiled and barbed thread within a cnidocyte

cnidocil

hairlike trigger of cnidocyte on surface

bioluminescence

results from chemical reactions that give off light rather than heat

protonephridia

two lateral canals with branches, making up distance excretory system in flatworms; dead end tubules lacking internal openings

flame cells

caps on branches of protonephridia

cerebral ganglia

clusters of nerve cell bodies that receive input from photoreceptors in eyespots and sensory cells

corona

ciliated crown that looks similar to a rotating wheel when beating

mastax

circular, muscular pharynx in mouth of rotifers

pedal glands

in foot, secrete a sticky substance that aids in attachment to a substrate

parthenogenesis

unfertilized diploid eggs that have not undergone meiotic division develop into females

foot

used for mollusk movement

visceral mass

contains internal organs and rests on top of the foot

mantle

fold of skin draped over the visceral mass, secretes a shel in those species that form shells

mantle cavity

houses delicate gills in a chamber

gills

filamentous organs that are specialized for gas exchange

open circulatory system

heart that pumps body fluid called hemolymph through vessels and into sinuses

metanephridia

excretory organs that remove nitrogen and other wastes

radula

unique protrusible tonguelike organ that has many teeth and is used to eat plants, scrape food particles off of rocks, or if mollusk is predatory, bore into shells of other species and tear flesh

veliger

free swimming larvae that has a rudimentary foot, shell, and mantle

closed circulatory system

blood flows throughout an animal entirely within a series of vessels (oxygen more readily available, quick pumping)

septum

seals off old chamber and secretes a new one

setae

chitinous bristles

parapodia

fleshy foot-like objects that are pushed into the substrate to provide traction during movement

giant axons

very large nerve cells that facilitate high-speed nerve conduction and rapid responses to stimuli

ecdysis

periodic molting of the exoskeleton

cuticle

nonliving cover that serves to both support and protect the animal

collagen

structural protein that makes up the majority of cuticle

stylets

sharp, piercing organs present in the mouth of nematode

exoskeleton

body covering of hard cuticle made of layers of chitin and protein

tagmata

body segment that have become fused into functional units

ommatidia

independent visual units that make up compound eyes of arthropods

tracheal system

organs that permit gas exchange

spiracles

pores on the body surface that provide openings to a series of finally branched air tubes within the body called trachea

Malpighian tubes

extensive tubes that extend from the digestive tract to the body cavity, where they are surrounded by hemolymph

cephalothorax

fused head and thorax

pedipalps

sensory, predatory, or reproductive functions

pedicel

narrow, waistline point of attachment joining cephalothorax and abdomen

entomology

study of insects

proboscis

coiled tongue of butterflies and moths

complete metamorphosis

change in body form during development

incomplete metamorphosis

gradual change of body form during development

carapace

hard protective fold covering the head that extends over most of the cephalothorax

nauplius

first larval stage

endoskeleton

internal hard skeletons composed of calcareous plates overlaid by thin skin

water vascular system

network of canals derived from coelom; uses hydraulic power which enables tube feet to extend and contract, allowing echinoderms to move very slowly

tube feet

function in movement, gas exchange, feeding, and excretion

madreporite

sievelike plate on the animals surface where water enters the water vascular system

ampulla

muscular sac at base of each tube that stores water

autonomy

ability to intentionally ditch a body part, such as a limb, that will eventually regenerate

notochord

single flexible rod that lies between the digestive tract and the nerve cord

pharyngeal slits

function as filter-feeding device, later developing into gills

incurrent siphon

used to draw water through the mouths of tunicates (filter feeders) using a ciliated pharynx

tunic

encloses whole animal, made of a protein and a cellulose-like material called tunicin