Lophotrochozoa - Week 7

Protosome

Animal with developmental mode distinguished by the development of the mouth from the blastopore; often characterized by spiral cleavage and by the body cavity forming when solid masses of mesoderm split

Blastopore

First indentation in blastula, which will become opening to the body cavity

Deuterostome

Animal with a developmental mode characterized by the development of the anus from the blastopore; also distinguished by radial cleavage and by the body cavity forming as out-pockets of mesodermal tissue; considered to be a monophyletic clade

Determinate cleavage

Found in most protosomes in which the type of tissue a cell will become is set early in development

Indeterminate cleavage

Found in deuterostomes in which early-development cells can become many different types of tissues; if cells completely split from each other during early development, each cell can grow an entirely new organism, resulting in identical twins

Lophophore

Specialized feeding apparatus consisting of ciliated tentacles that surround a mouth

Trochophore

Distinctive larval stage observed in some lophotrochozoan animals, including some annelids and mollusks, like sea slugs

Cephalization

Possession of a head region that contains sense organs

Incomplete

Type of gastrovascular cavity with only one opening, meaning it doesn’t have both a mouth and an anus

Hermaphroditic

Condition in which an individual functions as both male and female in sexual reproduction by producing both sperm and eggs

Flatworms

Hermaphroditic organisms that are bilaterally symmetrical with cephalization, an incomplete gastrovascular cavity, and no true body cavity

Corona

Ciliated structure that propels the animal through the water and moves food particles into the mouth

Mastax

Muscular pharynx that contains jaws for chewing up and grasping food particles; unique to rotifers

Rotifers

“Wheel-bearers”; organisms with a ciliated corona, mastax, and a complete digestive system

Nephridia

Excretory tubules in segmented worms

Clitellum

Sexual reproductive organ in earthworms which is composed of fused segments

Ganglion

Cluster/functional group of nerve cell bodies

Septa

Wall that divides a cavity of structure into smaller ones; in coral, one of the radial calcareous plates

Setae

Stiff structure that resembles a hair or bristle; in earthworms, hair-like structures that create traction against a substrate and aid in locomotion

Parapodia

In polychaete worms, a paired muscular appendage that functions in locomotion, sensation, or respiration; in sea slugs and other mollusks, a lateral extension of the foot that functions as an undulating fin for swimming

Cirri

Hair-like filament found in many animals; the appendages of barnacles; the barbel of some fish; feelers on both the anterior and posterior ends of clamworms

Pharynx

Part of earthworm that sucks in soil and detritus

Crop

Storage area for food in earthworms

Gizzard

Structure in earthworms that grinds it into a fine pulp

Intestine

Digestive tract in earthworms; full of dirt

Anus

Structure that expels undigested particles in earthworms

Metanephridia

Structure used for excretion in earthworms

Muscular foot

Structure used for movement in the phylum Mollusca

Mantle

Structure that drapes the visceral mass and secretes the shell (if one is present)

Visceral mass

Contains most of the internal organs of the phylum Mollusca; basically their body cavity

Chitons

Members of Class Polyplacophora; have reduced head

Torsion

Twisting of the organs within the shell

Cephalopods

Active marine predators with a highly developed brain and enlarged head as well as a head surrounded by tentacles that are modifications of the foot

Gastropoda

Largest and most diverse class in the Phylum Mollusca