Zoology, Terms for Exam 1

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adductor muscle scar

Region on interior of bivalve shell where the muscles attach to hold shell closed

Asconoid

Sponge body type; simple non-branching spongocoel

Byssus threads

Protein threads secreted by glands in the foot of bivalves; holds animal to substrate

cerrata

Secondary gill on dorsal surface of Opisthobranchs (Phylum Mollusca, Class Gastropoda)

Choanocyte

Flagellated cell lining interior canals of sponges; creates currents; captures particles in collar of microvilli held together by mucus; responsible for intracellular digestion and meiosis

coelom

Body cavity formed within mesoderm; created by layer of epithelium called the peritoneum; holds organs in place

colloblasts

Cells on tentacles of ctenophores that secrete glue for prey capture

corona

Ciliated "wheels" at anterior of rotifers; used for movement of water to capture suspended organic particles, such as bacteria, for feeding

ctenidium

Gill in molluscs; consists of an axis that holds layers of thin, vascularized sheets of tissue (has comb-like appearance, hence the name); also used for feeding in bivalves

dactylozooid

Defensive zooid with many nematocysts in polymorphic hydrozoa

diploblast

Development from embryos that have two layers of cells, the endoderm and ectoderm; adult organism has epidermis and gastrodermis (Cnidaria and Ctenophora are diploblastic)

epitoke

Sexual stage of some polychaete worms; separates from adult and swims up to spawn

eutely

Development in which all adults have the same, fixed number of cells (rotifers, nematodes, tardigrades)

flame bulb

Protonephridia found in flatworms, nemerteans, rotifers; ciliated "flame cell" pulls water from the coelom into a canal system for excretion; appears to function mostly for osmoregulation rather than excretion of wastes; Annelida have similar structure, but flame cell is flagellated (called a solenocyte)

foot

Muscular portion of mollusk used for movement

Gastrovascular cavity

Fluid filled cavity in Cnidaria (Ctenophores?)and Flatworms; serves for digestion and for hydroskeleton

gastrozooid

Feeding zooid of a polymorphic Hydrozoan

gonozooid

Reproductive zooid of a polymorphic Hyrdozoan

heteronomous

Annelid body type in which segments in different regions are specialize for certain functions

hinge & teeth

Portions of a bivalve shell; holds two sides of shell together

homonomous

Annelid body type in which segments are more or less the same

hydrostatic skeleton

Support structure in cnidarians and flatworms based on a fluid filled cavity surrounded by muscles that can put pressure on the cavity to stiffen and contract the animal; or release pressure to soften and extend the animal

labial palp

Extensions of tissue near the mouth of bivalves; selects appropriate particles to consume and creates pseudofeces of rejected particles

Leukonoid

Sponge body type characterized by extensively branching canals

mantle

Characteristic of molluscs; fold of epidermis that covers the vis the visceral mass and forms a cavity in which the ctenidia, anus, nephridiopore and gonopore are located; mantle secretes the shell and forms siphons, tentacles, and other structures

mantle cavity

Cavity in molluscs formed by the mantle; ctenidia lie in cavity and anus, gonopore, and nephridiopore open into cavity

medusa

Body form in Cnidaria; upside down sac with tentacles

mesoglea

Non-cellular layer of "jelly" and fibers between the epidermis and gastrodermis in cnidarian

mesohyl

Non-cellular material in the wall of a sponge; contains spicules, amoebocytes; lies between the choanocyte layer and the pinacocyte layer

mixonephridia

Structure in Annelids that serves for both excretion of wastes from mesonephridia to the outside of the body, as well as for transport of gametes

nematocyst

Organelle in cnidocytes of Cnidaria; when triggered by touch, shoots out a harpoon like hook with poisons, attached by a thread of protein; used to subdue prey and for defense

Osculum

Opening for excurrent water flow in sponges

osphradium

Sensory structure in bivalves; water flows that enters siphon flows first across this organ, which has chemosensors; enables siphon to "sniff out" directions in which food or mates might be found

Ostium

Opening for incurrent water flow in sponges

pallial line

Scar on shell that marks the edge where the mantle was attached

parapodia

Extensions of the body in polychaetes that serve as legs; contain setae

pericardial cavity

Region of coelom that encloses heart (in molluscs)

periostracum

External, organic layer of a molluscan shell

peristomium

The first segment in an Annelid; contains the mouth

polyp

Body type in Cnidaria; upright sac with tentacles

prostomium

"head" of a polychaete worm; region at anterior of peristomium

protonephridia

Simple kidney-like structures that serve as osmoregulatory and (in some) waste removal in flatworms, nematodes, nemerteans, and annelids)

pseudocoelom

Body cavity that is not lined with tissue and that does not originate from mesoderm

pseudofeces

Bolus of particles rejected by bivalve labial palps, bound up in mucus, and expelled into the mantle cavity

radula

Strip of stiff organic material holding chitinous teeth; used for feeding in molluscs

rhinophore

Chemosensory tentacles characteristic of Opisthobranchs

Segment

Repeating body unit in Annelids

setae

Chitinous bristles found in Annelids

siphon

Specialization of mantle for directing incurrent and excurrent water flow through body cavity in bivalves

Spicule

Crystal of CaCO3 or glass; forms skeleton in sponges

Spongocoel

Choanocyte cavities in sponges

statocysts

Organelle of maintenance of balance; found in Cnidaria, Ctenophores, molluscs

Syconoid

Spong body type with branched choanocyte lined channels

Torsion

Developmental process in gastropods that results in anus of adult located near mouth

Umbo

Oldest part of each valve in a bivalve shell

visceral mass

Tissue that contains gonad and digestive glands and structures in molluscs

Dioecious (gonochoristic)

Individual produces either eggs or sperm; includes members of phyla: nematodes, rotifers, annelids, molluscs, and tardigrades

Hermaphroditic

Individual produces eggs and sperm (serial hermaphrodite produces eggs and sperm but not at the same time); includes members of phyla: sponges, cnidarian, ctenophores, flatworms, annelida

Regneration

Ability to replace a body structure that has been lost

Trocophore larvae

Larval type characterized by an anterior tuft of cilia and a band of cilia; found in annelids and molluscs

Planula larvae

Larval stage in cnidaria

Veliger larvae

Larval stage in mollusca

Acoelomates

Animals that lack body cavities (sponges, cnidarian, ctenophores)

Pseudocoelomates

Animals that have a body cavity that is not derived from mesoderm; the cavity usually contains proteins, fibers, non-cellular material, and organs; nematodes, nemerteans, and rotifers

Coelomates

Organisms that have a body cavity derived from mesoderm; include annelids and molluscs and other "higher" animals

Asexual reproduction

Ability to reproduce via mitotically derived cells; common in sponges, cnidarian, Platyhelminthes, nemerteans, and annelida,

Parthenogenesis

Non-sexual reproduction in which females produce eggs that don't require fertilization and that produce only female offspring

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