chapter 33. phylum porifera sedentary suspension feeders, capturing food passed through the body...
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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