Chapter 33: invertebrates (sponges, cnidarians, and lophotrochozoans)

Invertebrate

Animals that lack a backbone

Phylum Porifera

Sponges, mostly marine and sessile; filter feeders

Sessile

Stationary, do not move

Filter Feeders

filter out food particles suspended in surrounding water as they draw it through their body

Spongocoel

Central cavity of a sponge

Osculum

Opening that connects spongocoel to the environment

Choanocyte

Flagellated collar cells that engulf bacteria and other food particles by phagocytosis, how sponges feed

Basal animal

Diverged from other animals early in the history of the group

Amoebocyte

Amoeba-like cells that move by pseudopodia, cell type of sponges

Hermaphrodite

Each individual functions as both male and female in reproduction by producing both sperm and egg

Sexual reproduction

produce sperm and eggs

Asexual reproduction

reproduce through budding or other form of “self-cloning”

Cribrostatin

Antibiotic produced by sponges that can kill cancer cells and penicillin-resistant strains of *Streptococcus* spp.

Phylum Cnidaria

Eumetazoan, true animals that have tissues; includes hydras, corals and jellies; feed through central digestive compartment

Gastrovascular cavity

Central digestive compartment that functions as both mouth and anus, utilized by Phylum Cnidaria

Polyp

Variation in Cnidaria body plan, largely sessile; mouth faces upward

Medusa

Variation in Cnidaria body plan, smaller and motile; mouth faces downward

Cnidocyte

Tentacles that protect Cnidaria and help capture prey

Cnidae

Capsule like organelles that are capable of exploding outward

Nematocyst

Stinging thread that explodes out of cnidae and can penetrate body of prey

Medusozoa

Clade of Cnidaria that contains Cnidarians that produce a medusa

Anthozoan

Clade of Cnidaria that contains Cnidarians that only exist as a polyp

Scyphozoan

Lower classification of Medusozoa that contains jellies

Cubozoan

Lower classification of Medusozoa that contains box jellies

Chironex fleckeri

Box jelly that is one of the deadliest organisms known, lives off the coast of Australia

Hydrozoan

Lower classification of Medusozoa that includes siphonophores, spends majority of life in polyp stage

Exoskeleton

Tough outer-covering secreted by some organisms for protection

Calcium Carbonate

Molecule that many exoskeletons are made up of

Coral bleaching

Increasing seawater temperatures clears out algal symbionts causing coral to turn white

Lophotrochozoans

Bilateria triploblastic animals; includes flatworms, rotifers, acanthocephalans, ectoprocts, brachiopods, molluscs, and annelids

Bilateral symmetry

the property of being divisible into symmetrical halves on either side of a unique plane

Triploblastic

having a body derived from three embryonic cell layers

Diploblastic

Having a body derived from two embryonic cell layers

Lophophore

a horseshoe-shaped structure bearing ciliated tentacles around the mouth

Trochophore

distinctive larval stage in some lophotrochozoans

Phylum Platyhelminthes

Flatworms; triploblastic, hermaphroditic, some are parasitic

Planarians

Phylum Platyhelminthes; free living flatworms that are not parasitic, light sensitive eyespots, can reproduce sexually hermaphroditic or asexually

Eyespots

Light sensitive areas on the heads of flatworms

Trematodes

Parasitic flatworms with complex life cycles, may have intermediate and final hosts; needs to find hosts to continue life cycle and reproduce

Tapeworms

Parasitic flatworms where adults live in human digestive systems, possess scolex and proglottids; acquired by eating undercooked meat

Scolex

\
“sucker” for attachment to human intestinal lining on tapeworms

Proglottids

Long ribbon of units, each unit consist of thousands of eggs; makes up “body” of tapeworm

Rotifers

Small multicellular organisms with specialized organ system, Phylum Syndermata

Alimentary canal

Digestive tube with 2 openings, utilized by rotifers

Parthenogenesis

asexual reproduction where females produce offspring from unfertilized eggs

Phylum Syndermata

Phylum containing rotifers and Acanthocephalans

Acanthocephalans

Parasitic organism, triploblastic “spiny headed worm”

Phylum Ectoprocta

Outside anus; commonly known as bryozoans (moss animal); have a coelom

Coelom

body cavity that is formed from tissues derived from the mesoderm

Phylum Brachiopoda

“lamp shells”; all are marine and bilateral, have a coelom

Phylum Mollusca

Consist of snails, slugs, oysters, clams, octopuses, and squids; 2nd most diverse phylum; all have similar body plan

Foot

muscular structure for movement

Visceral mass

contains internal organs of molluscs

Mantle

fold of tissue that may secrete a shell in molluscs

Penis fencing

Form of mating in flat worms where the loser is stabbed with the winners penis and impregnated

Clade Polyplacophora

Clade of Mollusca that contains chitons

Chitons

Marine organism with oval shaped body with shell and 8 dorsal plates, cling to rocks during low tide with foot as a suction cup

Dorsal plates

Protective plate on the dorsal side of an animal

Clade Gastropoda

Clade of mollusca that contains snails and slugs; most are marine and slow moving via rippling motion of their foot or cilia, most have shells

Clade Bivalvia

Clade of mollusca that contains clams and oysters, all are aquatic and most are sessile; shells are divided into 2 halves with no distinct head, eyes and sensory tentacles along outer edge of mantle

Adductor muscles

Draw 2 halves of bivalvia shells closed

Suspension feeder

Method of feeding where small food particles are trapped in mucus that coats the animals gills and cilia move it to mouth, utilized by clams and oysters

Clade Cephalopoda

Clade of mollusca that contains squids, octopuses, cuttlefish, and chambered nautiluses; marine predators with tentacles with modified foot that draws water into their mantle for locomotion; shell is generally reduced or missing, closed circulatory system

Excurrent siphon

modified foot of cephalopods that allows a jet of water to be pushed through the mantle

Chambered nautilus

Only living cephalopod with external shells

Closed circulatory system

Blood remains separate from other bodily fluids and cavity

Open circulatory system

Blood is mixed with other bodily fluids in the body cavity

Phylum Annelida

Segmented worms; marine, freshwater, and damp soil environments

Clade Errantia

Clade of Annelida; predatory mostly marine and mobile, feed on multicellular algae

Parapodia

“beside feet” of errantia

Cirri

fused bundles of cilia on errantia

Clade Sedentaria

Clade of Annelida; contains leeches and earthworms, less motile and will burrow in marine sediments and soil

Hirudin

chemical secreted by leeches to prevent blood coagulation

Fecal castings

Worm poop that is utilized as fertilizer

Regeneration

A way worms can reproduce asexually, when cut in half they can regenerate into two separate organisms

Clitellum

stores eggs, seen in sexually mature worms

Deuterostomia

What is the only animal group that has both invertebrates and vertebrates represented?