Invertebrate Diversity
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Transcript Invertebrate Diversity
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