Survey of Aquatic Invertebrates Lifestyles of the Spineless and Gilled.
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Transcript of Survey of Aquatic Invertebrates Lifestyles of the Spineless and Gilled.
Survey of Aquatic Invertebrates
Lifestyles
of the
Spineless and Gilled
Phylum Porifera the Sponges
• Asymmetrical • Sessile - attached to submerged rocks, sticks,
logs, or aquatic vegetation• Vary from marble-sized to elongated masses and
can grow to be thin or thick encrusting layers. • Their structure is supported by spicules, tiny
needle-like structures made of silicon that are distributed throughout the sponge body.
• Sensitive indicators of pollution. • Filter feeders• Little is known about them!
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Phylum Cnidaria, Class Hydrozoa the Hydra
• Radial Symmetry
• Carnivorous, kill with nematocysts (stinging cells)
• Somewhat sensitive to pollution
• May reproduce sexually orasexually
Phylum Platyhelminthesthe Flatworms
• Bilateral Symmetry
• Have 3 layers
• lack coelom, anus, circulatory and respiratory systems
• Very tolerant of pollution
Phylum Annelidathe Segmented Roundworms
• have external segments that correspond with repeated digestive and reproductive organs. • include leeches, aquatic earthworms, tubifex
worms and bristle worms • Very tolerant of pollution• Hermaphroditic; reproduce sexually by means of exchange
of gametes
Phylum Mollusca
• Bilateral Symmetry
• Specialized Foot
• Mantle
• Radula
• 2 Aquatic Classes– Pelecypoda (Bivalvia – clams, mussels)– Gastropoda (snails)
Freshwater Bivalves
Freshwater Bivalves – Life History
• Freshwater mussels feed by filtering algae and small particles from the water.
• Most are somewhat sensitive to pollution.• Most species have a larval stage that is parasitic on
fish. • Larvae are released by the female mussel and must
locate a certain fish species or die.• They usually attach to the host fish's gills or fins
where they remain for a few weeks or months. • Larval mussels rarely harm infected fish under
natural conditions. • If essential fish species are removed from the
habitat, mussels will not be able to reproduce.
Freshwater Bivalves – their life cycle illustrated
Bivalves can tell us alot about history!
http://www.texasbeyondhistory.net/jbwhite/musselmania/flash.html
Class Gastropoda – the Snails
• May be carnivorous or herbivorous.• Hermaphroditic• Most are highly tolerant of pollution.• May or may not possess an operculum, or
“lid” that it can close its shell with. • When looking at the shell’s opening with
the narrow end up, the opening may be on the right of the spiral (dextral) or to the left (sinistral)
Class Gastropoda – the Snails
• Planorbid Snails – coiled flat, no operculum • Lymnaeid Snails – dextral, no operculum• Physid Snails – sinistral, no operculum
Bithynid Snail
Dextralstiff operculum, with well-centered concentric rings
Viviparid Snail
Dextral – flexible operculum, with off-center concentric rings.
Hydrobiid Snail
Dextral – has flexible operculum with multispiral rings
Pleurocerid Snail
Dextral – very flexible operculum that recedes deep into shell, paucispiral rings
Planorbid Snail
Coiled flat, no operculum
Lymnaeid Snail
Dextral, no operculum
Physid Snails
sinistral, no operculum
Phylum Arthropoda• Bilateral Symmetry• Jointed Appendages• Exoskeleton of chitin• Most important aquatic groups – • Arachnida Crustacea Insecta (very tolerant) (somewhat tolerant) (variable tolerance)
Water Mites Scuds Water Bugs (tolerant) Water Spiders Isopods Water Beetles (sensitive) Seed Shrimp Odonate nymphs (varies) Grass Shrimp Plecoptera nymphs
Crayfish (extremely sensitive) Ephemeroptera nymphs
(extremely sensitive)
Megaloptera nymphs (sensitive) Diptera larvae (very tolerant)
Phylum Chordata • Bilateral symmetry• Possess notochord, chambered heart,
closed circulatory system• Includes vertebrates.• Some “quasi-vertebrate” examples:
– Lampreys
– Tadpoles
No paired fins, no jaws. Gill slits, cartilage skeletonOur native Southern Brook Lamprey (Ichthyomyzon gagei, pictured) has a larval stage that is a detritivore; adults are ephemeral, do not eat.
All larval amphibians are very primitive in that they lack jaws, paired fins. All are Detritivore until they get hind legs, and jaws, then become predaceous.
Bufo valliceps Gulf Coast Toad
Rana catesbianaBullfrog
Rana sphenocephalaSouthern Leopard Frog
Rana clamitansBronze Frog
http://www.bgsd.k12.wa.us/hml/jr_cam/macros/amc/index.html
http://www.ncsu.edu/sciencejunction/depot/experiments/water/tutorial/tutorialmacro.html
http://rock.geo.csuohio.edu/norp/bmi.htm
http://www.cod.edu/people/faculty/chenpe/RiverWatch/MBI_calculator.html