Chapter 33

Phylum PoriferaSedentary suspension

feeders, capturing food passed through the body Water into spongocel,

out thru osculum Both vary in number

Sequential hemaphroditesEggs maintained in

mesophyll, sperm out thru osculum

Motile larvae find substrate to develop

Celllular level of organizationChoanocytes, or flagellated

collar cells, line interior of spongocel to move water in

Amoebocytes take food from water and choanocytes to digest it

Produce antibiotic related compounds

Classes of PoriferaClass Calcarea

Spicules, made by amoebocytes, of CaCO3E.g. Grantia

Class HexacinellidaSpicules, made of silicaReferred to as ‘glass sponges’

Class DemospongiaeSkeleton of silica spicules, flexible spongin, or

bothReferred to as ‘bath spongs’E.g. Spongia

Phylum CnidariaSessile and motile formsDiplobalstic and radially

symmetricalContain a gastrovascular

cavity, from endodermSac like body plan

Simplistic muscle and nerve tissuesGastroderm contracts

with closed mouth=shape change coordinated by nerve net Arranged radially

Cnidocytes capture preyContain nematocysts,

which penetrate, stick to, or tangle prey

Polyp or medusa body formSome 1, other, or both

in life

Class HydrozoaClass Scyphozoa

Dominate medusa form and minor polyp stageAll marineE.g. jellyfish

Class CubozoaBox-shaped medusa stage with complex eyes and

potent venomClass Anthozoa

Polyp stage only, mostly colonial and sessileAll marineE.g. sea anemones and coral

Classes of Cnidarians

Class HydrozoaDominate polyp form and minor medusa

stageMost marine, some freshwaterHydra

Freshwater species only exhibit polyp formCan be motile

ObeliaColony of chitinous covered polyps

Portugese man-of-warColony of polypsOriginal is air bladder and rest for feeding and

reproduction

Phylum Platyhelminthes Bilateral, tribloblastic, acoelomates with

sac body planDemonstrates cephalization and ladder like

nervous systemOrgan system variations

HermaphroditicNo specialized circulatory or respiratory organs

Gastrovascular cavity branches throughout body to distribute material to cells

Excretory system of flame cells for osmoregulation Reduced in parasitic forms

Classes of PlatyhelminthesClass Tubellaria

Most marine, some freshwater, some terrestrial Specialized sense organs and nervous system

Eyespot, auricle, pharynx, and varies reproductively E.g. planaria (Dugesia)

Class Trematoda Parsitic, many with suckers to aid in attachment Body mostly reproductive organs

Life cycle alters between sexual and asexual forms (intermediate host) E.g. Schistosoma, blood flukes, evade detection by changing

surface proteinsClass Cestoda

Parasitic in vertebrates with scolex to attach to intestines Lack mouth and gastrovascular cavity, absorb through body Chains of proglottids, sacs of sex organs that fill with eggs

and exit in feces Can form cyst stages to survive as larvae E.g. Taenia (dog/cat tapeworm)

Phylum NematodaNon-segmented, pseudocoelomates, covered by a

cuticleTube within a tube body plan characterized by

an alimentary canal (mouth and anus) Lack a circulatory systemReproduce sexually with internal fertilization

Male and female species separate and distinct in sizeZygotes able to survive harsh

conditionsLongitudinal muscles =

whip-like movement

Nematode ExamplesTrichinella spiralis (trichinosis)

Juvenile worms encyst in pig muscle, humans consumeAdults burrow through intestines into lymph system

Caenorhabditis elegans (C. elegans)Popular model for genetic research

Enterobius vermicularis (pinworms)Common childhood disease

Dinofilaria immitis (dog heartworms)Wucheria bancrofti (elephantiasis)

Transmitted by mosquitos and live in lymph systemsNecatur americanus (hookworms)

Phylum MolluscaMostly marine, some freshwater or terrestrialSoft-bodied, but secrete a shell of CaCO3 (some lost)Coelomates with 3 part body plan

Foot: muscular organ for locomotion, attachment, or feeding

Visceral mass: contains internal organsMantle: suurounds visceral mass and may secrete shell;

develops gills or lungsFeed via a radulaMost separate sexes, but snails are hermaphroditesOpen circulatory system, blood not confined to

vesselsNeural ganglia connected by nerve cord

Classes of MolluscsClass Polyplacophora

Body of dorsal plates, but unsegmented; no head but radulaClass Gastropoda

Herbivore’s uses radula to scrape, carnivorous to bore thru prey

Developed head with eyes and demonstrates torsionSome hermaphroditic, but require another individual

Class BivalviaTwo part shells secreted by mantle and controlled by

muscles Can see growth rings; made of protein

Little cephalization, no head or radula Gills for gas exchange, most suspension feeders

Separate sexes

Class CephalopodaActive predators with

beak like jaws and poisoned saliva

Foot modified into a siphon to direct movement

Closed circulatory system, well developed sense organs, and a brain

Mantle covers visceral mass, but may be internal or missingNautiluses are last

surviving ammonites, posses shells

Phylum AnnelidaSegmented worms, separated by partitions called

septaCoelomates with a closed circulatory systemSolid ventral nerve cord, anterior brain, and a

ganglia in each segmentNephridia, coiled tubes for excretion in each

segmentDigestive stystem with pharynx, stomach, and

intestinesSome with setae, bristles, and parapodia, paddle-

like appendages, for movement

Classes of AnnelidsClass Polychaeta

Each segment with parapodia and setaeMarine animals that are mostly filter feeders, some

predatorsDefined cephalization with eyes, sense organs, and jaws

Class OligochaetaMoist environments to allow gas exchangeInclude earthworms

Hermaphroditic, posses a clitellum to aid cross-fertilization

Class HirudineaMost freshwater, some marine and terrestrialInvertebrate predators or parasites

Slit skin with jaws or dissolve hole with enzymes Use anesthetic so undetectable and hirudin, an anticoagulant

Phylum ArthropodaSpecialized jointed appendagesHard exoskeleton of chitin and protein

Sites for muscle attachment, protection, and stops desiccation

Limits growth so must molt = energetically expensive

Segmented bodies allows organ and system specializations

Developed nervous system for sight, smell, and touch

Open circulatory systemRespiratory systems vary between tubes, lungs,

and gills

Subphyla of ArthropodsSubphylum Crustacea Subphylum Chelicerata

Mostly marine with gillsHead with compound

eyes & 5 appendage pairs2 pairs antennae1 mandible and 2

mandible for feedingWalking legs on thoraxIncludes Isopods,

Copepods and Krill, Barnacles, and Decapods

Most collectively called arachnids

No antennae and simple eyes

Specialized appendages1 pair for feeding =

chelicerae1 pair sensory function =

pedipalps4 pair walking legs

Book lungs for respiration

Subphyla of ArthropodsSubphylum Myriapoda Subphylum Hexapoda1 Pair of antennae, 1 pair

of madibles, and 2 pairs maxillae

Class DiplopodaMillipedes are herbivores

with 2 pairs of legs a segment

Class Chilopoda Centipedes are

carnivorous with 1 pair of legs a segment; poison claws on first segment

Class Insecta1 or 2 pairs of wings from

thorax, cuticle extensions not appendages

Advertize with colors , sounds, or odors for reproduction

Metamorphosis to reduce competition within a speciesComplete (different and

direct) or incomplete (similar and stages)

Phylum EchinodermataDeuterostomes with a spiny endoskeleton

covered by calcareous plates with spinesWater vascular system includes tube feet

for locomotion, feeding, and gas exchangeLack complex circulatory, respiratory, and

excretory systemsInternal and external parts radiate from

center of organismNot true symmetry, larvae are bilateral and

sieve plate offset in adultLack cephalization, nervous system is ring

with radial nerves in each arm

Classes of EchinodermsCan regrow lost arms,

turns stomach inside out to eat

Long, flexible arms for movement

Mouth is a jaw like structure, tube feet in rows

Mouth faces up and arms for suspension feeding

Lack spines, tube feet around mouth for feeding

Armless with 5-sided organization, ringed by spines