Lecture 10

• Phylum Porifera

  • Sponges
  • marine
  • feed by filtering (selectively)
  • algal endosymbiosis
  • important food predators
  • not photosynthetic
• Phylum Cnidaria

  • jellyfish, anemones, corals, hydroids
  • most marine
  • Hydrozoa appear in freshwater
  • have cnidocytes
  • hydra
• cnidocytes -> specialized cells that fire filaments to capture prey
• Hydra

  • common cnidarian in streams, wetlands, and lakes
  • can float in water column but typically attach to benthic substrate or plants
  • feed on small invertebrates
• Phylum Platyhelminthes (flat worms)

  • turbelia
  • free-living
  • mostly predators
  • Trematoda
  • flukes
  • parasites
  • Cestoda
• Phylum Nemertea

  • non-segmented worms
  • mostly marine
  • predators
• Schistosoma

  • fluke
  • has different hosts for each life stage
• Phylum Gastrotricha

  • found in benthic habitats
  • shallow lakes, ponds, and wetlands
  • feed on bacteria, protozoa, algae, and detritus
  • can be super abundant
  • eggs are resistant to drying, heating, and freezing
• Phylum Rotifera

  • found in all freshwater
  • multiple feeding strategies
  • major food source for many zooplankton
• Phylum Nematoda

  • Round worms
  • benthic
  • can live in extreme habitats
  • many freshwater are parasitic
  • non-segmented, cylindrical
• Phylum Nematomorpha

  • parasites
  • horse wire worms
  • macro in size
• in Phylum Mollusca there are two classes: Gastropoda and Bivalia
• Gastropoda

  • snails
  • mollusca
  • primary grazers
  • have radula
  • important prey and parasite hosts
  • more diverse class
• Primary Grazers

  • pull algae off of benthic surfaces
  • have radula
  • can control primary production locally
• Bivalvia

  • Mollusca
  • shell has two halves
  • burrow in sediment of stream and lake benthos
  • have parasitic larvae
  • host specific
• What does Phylum Annelidia include?

  Oligochaetes and leeches
• Oligochaetes

  • similar to terrestrial earthworms
  • burrow in sediment
  • eat detritus
  • tolerant of low O2 and pollution
• Leeches (Hirundinae)

  • predators
  • feed on mollusks, insects, worms
  • some parasitic
  • found in slow moving waters
• the Bryozoans include:

  Phylum Entoprocta and Ectoprocta
• Phyla Entoprocta and Ectoprocta

  • Sessile
  • eat suspended food particles
  • primarily marine
  • can form large colonies
• Phylum Tardigrada (water bears)

  • microscopic
  • can withstand drying
  • usually benthic
• What are the three subphyla of Arthropoda?

  Chelicerata, Uniramia, and Crustacea
• What are the three key characteristics of Arthropoda?

  • Three body segments
  • Chitonous exoskeleton
  • highly diverse
• Arachnida

  • water mites and spiders
  • no true water spiders
• Uniramia collembola (springtails)

  • semi-aquatic
  • along margins of lakes and biofilms
  • feed on detritus and biofilms
• most insects have an aquatic stage
• Uniramia insecta

  • diverse
  • larvae are aquatic
  • diverse feeding strategies
  • range of habitats
• Crustacea

  • diverse freshwater forms
  • hard chitinous exoskeleton reinforced by calcium
  • many body segments
• Crustaeca Ostracoda (seed shrimp)

  • benthic
  • covered in chitin or calcareous carapace
  • in all types of aquatic habitats
  • eat detritus and algae
  • important prey source (very abundant)
• Crustaeca Copepods

  • micro
  • mostly benthic some pelagic
  • varied feeding strategies
  • have complex behaviour
  • predator avoidance, mating, foraging
• Crustaeca Branchiopoda

  • water fleas (cladoceran) and shrimps
  • found in pelagic zone of lakes
• Cladocerans (water fleas)

  • zooplankton
  • filter water for microorganisms
  • include Daphnia
  • exhibit variety of behaviours
  • vertical migrations to avoid predators
• Crustaeca Decapoda

  • crayfish, crabs and shrimp
  • large and long-lived
  • have well developed Chelae (pincers)
  • omnivores
  • important prey for fish and large animals
• Isopods (sow and pill bugs)

  • dorsally flattened
  • in springs, streams, and groundwaters
  • detrivores and scavengers
• Amphipods (scuds and sideswimmers)

  • laterally flattened
  • omnivore
  • nocturnal
  • can be very abundant where fish arent
• Fish are the most diverse aquatic vertebrates and includes jawless fish and jawed fish
• bony fish are most diverse in freshwaters
• the lateral line in fish detects vibrations from water
• wider fish are lentic
• flat fish are benthic