BIOL1131 Lecture Notes - Lecture 2: Internal Fertilization, Photic Zone, Filter Feeder
7 Jun 2018
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Life in the Aquatic
Walked in 10mins late, go over first 10mins!!
• Benefits of a Marine Life
o Stable environment
o Iso-osmotic conditions
o No desiccation
o Support for body tissues
o Surrounded by food
• Costs of a Marine Life
o Lower oxygen concentration
▪ Solution = gills
o Wind, waves and currents
▪ Solution = being sessile
• A uniquely marine (aquatic) lifestyle
• E.g. sponges, hydroids and corals, oysters, barnacles…
• Benefits:
o No energy required to stay still
o No energy required to go catch food
o Have an established place to live
• Costs
o Can’t move if conditions change
o May be an easy target for predators
o May be prone to disturbance
• All animals are dependent on autotrophs for energy
o Most marine animals live in the photic zone where photosynthesis is
possible
o Deep sea animals derive energy from detritus or sulphur fixing bacteria
• Feeding strategies
o Being surrounded by food allows for suspension feeding
o Suspension feeders remove particles from the water column with the aid
of filters, traps, sticky surfaces…
▪ E.g. sponges, some cnidarians, some annelids, many molluscs, some
crustaceans, some echinoderms, a few chordates
o Deposit feeding
▪ Animals remove detritus from sediments with feeding appendages
• Reproductive strategies in the sea
o Indirect development
▪ Broadcast spawning
• External fertilization
• Dispersive larval stage
• Some poriferans, many cnidarians, some annelids, many
molluscs, most echinoderms, some chordates.
▪ Mixed development
• Release of larvae from egg capsules
• Internal fertilization
• More advanced larva released
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