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Chapter 33
Phylum Porifera
 Sedentary suspension
feeders, capturing food
passed through the body
 Water into spongocel, out
thru osculum

Both vary in number
 Sequential hemaphrodites
 Eggs maintained in
mesophyll, sperm out thru
osculum
 Motile larvae find substrate
to develop
 Celllular level of organization
 Choanocytes, 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 Porifera
 Class Calcarea
 Spicules, made by amoebocytes, of CaCO3
 E.g. Grantia
 Class Hexacinellida
 Spicules, made of silica
 Referred to as ‘glass sponges’
 Class Demospongiae
 Skeleton of silica spicules, flexible spongin, or both
 Referred to as ‘bath spongs’
 E.g. Spongia
Phylum Cnidaria
 Sessile and motile forms
 Diplobalstic and radially
symmetrical
 Contain a gastrovascular
cavity, from endoderm
 Cnidocytes capture prey
 Sac like body plan
 Contain nematocysts,
 Simplistic muscle and nerve
which penetrate, stick
tissues
to, or tangle prey
 Gastroderm contracts with
 Polyp or medusa body
closed mouth=shape change
form
coordinated by nerve net
 Some 1, other, or both in
 Arranged radially
life
Classes of Cnidarians
 Class Hydrozoa
 Class Scyphozoa
 Dominate medusa form and minor polyp stage
 All marine
 E.g. jellyfish
 Class Cubozoa
 Box-shaped medusa stage with complex eyes and potent
venom
 Class Anthozoa
 Polyp stage only, mostly colonial and sessile
 All marine
 E.g. sea anemones and coral
Class Hydrozoa
 Dominate polyp form and minor medusa
stage
 Most marine, some freshwater
 Hydra
 Freshwater species only exhibit polyp form
 Can be motile
 Obelia
 Colony of chitinous covered polyps
 Portugese man-of-war
 Colony of polyps
 Original is air bladder and rest for feeding and reproduction
Phylum Platyhelminthes
 Bilateral, tribloblastic, acoelomates with sac body
plan
 Demonstrates cephalization and ladder like nervous
system
 Organ system variations
 Hermaphroditic
 No 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 Platyhelminthes
 Class 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
proteins
 Class 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 Nematoda
 Non-segmented, pseudocoelomates, covered by a cuticle
 Tube within a tube body plan characterized by an
alimentary canal (mouth and anus)
 Lack a circulatory system
 Reproduce sexually with internal fertilization
 Male and female species separate and distinct in size
 Zygotes able to survive harsh
conditions
 Longitudinal muscles =
whip-like movement
Nematode Examples
 Trichinella spiralis (trichinosis)
 Juvenile worms encyst in pig muscle, humans consume
 Adults 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 systems
 Necatur americanus (hookworms)
Phylum Mollusca
 Mostly marine, some freshwater or terrestrial
 Soft-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 organs
 Mantle: suurounds visceral mass and may secrete shell;
develops gills or lungs
 Feed via a radula
 Most separate sexes, but snails are hermaphrodites
 Open circulatory system, blood not confined to vessels
 Neural ganglia connected by nerve cord
Classes of Molluscs
 Class Polyplacophora
 Body of dorsal plates, but unsegmented; no head but radula
 Class Gastropoda
 Herbivore’s uses radula to scrape, carnivorous to bore thru prey
 Developed head with eyes and demonstrates torsion
 Some hermaphroditic, but require another individual
 Class Bivalvia
 Two 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 Cephalopoda
 Active 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
missing
 Nautiluses are last surviving
ammonites, posses shells
Phylum Annelida
 Segmented worms, separated by partitions called septa
 Coelomates with a closed circulatory system
 Solid ventral nerve cord, anterior brain, and a ganglia in
each segment
 Nephridia, coiled tubes for excretion in each segment
 Digestive stystem with pharynx, stomach, and intestines
 Some with setae, bristles, and parapodia, paddle-like
appendages, for movement
Classes of Annelids
 Class Polychaeta
 Each segment with parapodia and setae
 Marine animals that are mostly filter feeders, some predators
 Defined cephalization with eyes, sense organs, and jaws
 Class Oligochaeta
 Moist environments to allow gas exchange
 Include earthworms

Hermaphroditic, posses a clitellum to aid cross-fertilization
 Class Hirudinea
 Most freshwater, some marine and terrestrial
 Invertebrate predators or parasites


Slit skin with jaws or dissolve hole with enzymes
Use anesthetic so undetectable and hirudin, an anticoagulant
Phylum Arthropoda
 Specialized jointed appendages
 Hard 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 system
 Respiratory systems vary between tubes, lungs, and
gills
Subphyla of Arthropods
Subphylum Crustacea
Subphylum Chelicerata
 Mostly marine with gills
 Most collectively called
 Head with compound eyes &
arachnids
 No antennae and simple eyes
 Specialized appendages
5 appendage pairs
 2 pairs antennae
 1 mandible and 2 mandible
for feeding
 Walking legs on thorax
 Includes Isopods, Copepods
and Krill, Barnacles, and
Decapods
 1 pair for feeding = chelicerae
 1 pair sensory function =
pedipalps
 4 pair walking legs
 Book lungs for respiration
Subphyla of Arthropods
Subphylum Myriapoda
Subphylum Hexapoda
 1 Pair of antennae, 1 pair of
 Class Insecta
 1 or 2 pairs of wings from
thorax, cuticle extensions not
appendages
 Advertize with colors ,
sounds, or odors for
reproduction
 Metamorphosis to reduce
madibles, and 2 pairs
maxillae
 Class Diplopoda
 Millipedes 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
competition within a species
 Complete (different and
direct) or incomplete
(similar and stages)
Phylum Echinodermata
 Deuterostomes with a spiny endoskeleton covered by
calcareous plates with spines
 Water vascular system includes tube feet for
locomotion, feeding, and gas exchange
 Lack complex circulatory, respiratory, and excretory
systems
 Internal and external parts radiate from center of
organism
 Not true symmetry, larvae are bilateral and sieve plate
offset in adult
 Lack cephalization, nervous system is ring with radial
nerves in each arm
Classes of Echinoderms
 Can 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