Chapter 31 Protostome Animals

protostome

a major lineage of bilaterian animals including arthropods, mollusks, and annelids. Sister group to deuterostomes

lophotrochozoan

a clade within protostomes that includes animals such as mollusks and annelids, characterized by a trochophore larval stage or a lophophore feeding structure.

lophophore

a specialized feeding structure found in some lophotrochozoans and used in suspension (filter) feeding

trochophore

a larva with a. ring of cilia around its middle that is found in some lophotrochozoans

rotifera

show the trochophore stage even as adults, have a wheel of cilia around the head that moves water and food particles into the mouth, one of the smallest animals in existence, hard to tell apart from the protists cilia

playhelminthes (flatworms)

have a flat body that is an adaptation to allow for the ease of movement of gases or nutrients across their skins, do not need a circulatory system, simple digestive system, ACOELOMATES

annelida

a phylum of segmented worms characterized by a body divided into segments, a well-developed coelom, and a complete digestive system.

chaetae

bristle like extensions found in some annelids

parapodia

appendages found in some annelids from which bristle-like structures (chaetae) extend

mullusca

a phylum of invertebrate animals that includes snails, clams, and octopuses, characterized by a soft body, often with a hard shell, and a muscular foot.

foot

one of the three main parts of the mollusk body; a muscular appendage, used for movements such as crawling and/or burrowing into sediment

visceral mass

one of the three main parts of the mollusk body; contains most of the internal organs and external gill

mantle

one of the three main parts of the mollusk body; the thick outer tissue that protects the visceral mass and may secrete a calcium carbonate shell

radula

a rasping feeding appendage in mollusks such as gastropods (snails, slugs)

exoskeleton

a hard covering secreted on the outside of the body, used for body support, protection, and muscle attachment

cuticle

a protective coating secreted by the outermost layer of cells of an animal or a plant; often functions to reduce evaporative water loss

molting

a method of body growth, characteristic of ecdysozoans, that involves the shedding of an external protective cuticle (exoskeleton in arthropods), expansion of the soft body and growth of a new external cuticle

nematodes (round worms)

distinguished by an unsegmented body with a pseudocoelom and no appendages

arthopoda

distinguished by a segmented body; hard, jointed exoskeleton; paired, jointed appendages; and an extensive body cavity called a hemocoel

tagmata

prominent body regions in arthropods, such as the head, thorax, and abdomen in insects

head

the anteriormost region of many bilaterian animals, usually containing specialized sensory structures and the brain

thorax

a region of the body; in arthropods, located between the head and abdomen; in vertebrates, including humans, the chest

abdomen

a region of the body; in arthropods located posterior to the thorax

cephalothorax

the body region that is formed by the fusion of the head and thorax, anterior to the abdomen

metaphorphosis

a drastic transition from one developmental stage to another, such as from the larval to the adult form of an animal

pupa (pupae)

insects undergoing complete metamorphosis, the life stage during which the juvenile form metamorphoses into the adult form

Bryozoans

an example of an organism with a lophophore structure

Tubellaria

a lineage of flatworm that mostly feed on dead organic matter, have a blind digestive system, and are free living

trematoda (flukes)

a lineage of flatworm that is parasitic, sexually dimorphic bodied, and will exist in multiple organisms

cestoda

a lineage of flatworm that live in the guts of animals and feed on the food being digested by the animal (tapeworms!)

Polychaeta

referring to the many bristles along the sides of the worm that aid in moving through their environment

Oligochaeta

black tiny bristles that have the same purpose as the polychaete’s bristles, hermaphroditic

hirudinea (leeches)

no bristles, aquatic, about half are ectoparasites

chitons

mollusks with dorsal shells made of plates, also known as polyplacophora, have 8 plates that make up their shell, mostly graze on rocks

bivalves

mostly immobile, some attach to substrates and stay there most of their life

gastropods (slugs and snails)

live in marine, fresh water, and terrestrial environments, slugs are the only ones who do not have a shell, word means bellyfeet

cephalopods

lineage of mollusks including squid, octopuses, and cuttlefish. have large brains, excellent vision, arms and tentacles, no shell

myriapoda

bodies are composed of repeated segments typically with one pair of appendages per segment (centipedes) or two pairs (millipedes) they lack specialized body segments

insecta

have three main body segments (tegmeta), the head, thorax, and abdoment. they possess three pairs of walking appendages and one pair of antennae. exhibit a vast diversity and are adapted to various environments

crustacea

have branched appendages and two pair of antennae. typically have 3 body segments head, thorax, and abdomen although some may only have cephalothorax and abdomen (shrimps, lobsters, crabs)

chelicerata

have two main body segments (cephalothorax and abdomen) and four pairs of walking appendages. they lack antennae but have specialized appendages called chelicerae for capturing prey (spiders, scorpions, and horseshoe crabs)

Complete metamorphosis

the juvenile stage (larva) looks and behaves differently from the adult, often inhabiting different environments. this adaptation reduces competition for resources between juveniles and adults

incomplete metamorphosis

the juvenile stage (nymph) resembles the adult but is smaller and not fully developed