phylum rotifera - faculty€¦ · phylum rotifera • freshwater, freeliving (most), few marine •...
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Phylum Rotifera• Freshwater, freeliving (most), few
marine• Linked to Lophotrochozoa• Many habitats and shapes• Many interstitial• Roto-feeders• Telescopic; semi-flexible• Protonephridia and diffusion• Reproduction: parthenogenesis
General Body Plan
Ciliated Head= Corona
Often a ringed cuticle to allow for contraction (antenna)
Jawed Mastax for chewing
Flame cells and bladder
movie
Rotifer Reproduction
•Most Dioecious
•Some parthenogenetic
heavy-shelled dormant egg, much yolk; dormant egg survives the winter
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Lophophorates
• Ciliated Lophophore- feeding structure• Hollow lophophore tentacles are projections of
the coelom (respiratory)• Surrounds mouth
Phylum Bryozoa
• “Ectoprocta”• 4000 species, both
FW and Marine• Colonial-
– Zoecium– Jack-in-the-box– operculum
Phylum Brachiopoda• 325 extant, 12,000 extinct• Two calcareous shells: Top/bottom, not right/left
Phylum Mollusca: snails, slugs, chitons, clams, octopus and squid
• Trend toward rounder body: low SA/vol ratio• Lack of segmentation (except Neopilina)• Hypothetical Molluscan ancestor
– Mantle and mantle cavity, shell– Muscular foot: sensory and locomotory– Visceral Mass
• Cephalization: sensory and feeding• Gills (most)• Complete GI w/ glands, radula• Open circ. system*: heart and haemocoel• Metanephridium• Separate sexes
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“HAM”The trochophore larva
2nd larval stage-Veliger larva of snail
Shell and Mantle 3 layers
1. Periostracum
2. Prismatic
3. Nacreous
Radula
Class ScaphopodaClass Monoplacophora
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Class Polyplacophora: chitons• 600 living species, mostly intertidal• Most similar to ancestral mollusc• Broad-footed herbivores• 8 overlapping plates• Very little cephalization: no eyes or tentacles,
small head w/ radula
Cryptochiton stelleri- Gumboot Chiton
Class Gastropoda: snails, slugs, limpets
• Largest molluscan class, 40,000 species• Mobile: Herbivores and Carnivores
• 3 important changes from ancestral mollusc– Greater cephalization: affects sensory and locomotion
– Asymmetrical spiral shell: portable protection– Torsion: realignment of body with shell
• Feeding strategies and specializations• Gills or “lungs”
Torsion- do you see a problem?(and de-torsion)
Pulmonate gastropods-mantle cavity modified into lung
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Class Bivalvia: clams
• Laterally compressed w/dorsal hinge• Very large mantle cavity: use of gills for
respiration and suspension (filter) feeding– Incurrent and excurrent siphons
• No radula or distinct head present• Pearls: require inner nacreous
layer
CtenidiaHighly modified for respiration AND feeding
Water/Food path
Internal Anatomy Burrowing LocomotionBurrowing Locomotion
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Cl. Cephalopoda: nautilus, squid, octopus• 650 species, extinct members include Ammonites (65
mya)• Predators• Swimming lifestyle: jet propulsion• Reduced or absent shell• Closed circulatory system• Cephalization: sensory, movement, learning• Foot gives rise to funnel• Arms that are probably derived from the molluscan head • Chitinous beaks• Direct development (larvae?)• Cephalopod eye: convergence
Squid Internal Anatomy
DosidicusDosidicus gigasgigas-- Humboldt SquidHumboldt Squid Giant Squids
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Architeuthis