L19 - Benthic Invertebrates Flashcards
What are the benthic habitats?
Benthos, epibenthic, infauna
What is benthos?
Associated with the sea bed
What is epibenthic?
Attached to a hard substratum or rooted to a shallow depth below seabed surface
What are benthic invertebrate feeding modes?
Herbivores, carnivores, deposit feeders, filter feeders.
What is infauna?
In sediment
What do suspension (filter) feeders do?
They capture particles from water. Passive - use existing current, active generate own current
What are some examples of important filter feeders?
Bivalves, bryozoans, cirripedes, corals, holothurians, ophiuroids, polychaetes, sponges, tunicates
What is the class cirripedia: super order thoracica?
Two orders, sessilia: acorn barnacles, pedunculata: goose barnacles. Morphology of adults : a shrimp that has cemented its head to a rock and grown plates around itself
What are brittle star beds?
Some spp. can be found in huge numbers in particular areas (>1000m-2). In british waters, mainly Ophiothrix fragilis and Ophiocomina nigra. Variable sizes, but can cover several km2
What are the two clades of Polychaetes?
Errantia and Sedentaria
What are the Sedentaria?
Include colonial, reef-building forms with fans of head tentacles like the serpulids and sabellariids.
What do deposit feeders do?
Ingest sediment and digest organic content. Many are also scavengers
What are some examples of important deposit feeders?
Bivalves, crustaceans, gastropods, holothurians, polychaetes
What are isopods and amphipods generally?
Mostly marine, detritivores/scavengers
What are Isopoda?
Dorso-ventrally flattened, aquatic species are benthic. Numerous deep sea spp (some get very large). Some important parisitic forms.
What are Amphipoda?
Laterally compressed, can be broadly divided into gammarids and hyperiids. Gammarids (~90% all amphipods) - almost all aquatic environments, but mainly benthic. Hyperiids are all planktonic
What are gastropods?
Radula, unique to molluscs. Ribbon of chitin covered in rows of backwards-facing teeth with a moveable fleshy base. As teeth wear out, they are replaced by new rows from behind.
What is aristotle’s lantern?
Centrally located jaw on oral surface. Surrounded by 5 rigid teeth. Named by aristotle
Recruitment of larval urchins to removal of urchin predators (otters, lobsters) cycle?
Increased sea urchin density, destructive grazing, barren grounds, disease in urchins, mass urchin mortality, recruitment and re-establishment of kelp, kelp beds.
What are examples of irregular echinoids?
Sand dollars (Clypeasteroida) and Heart urchins (Spatangoida)
How do cephalopods feed?
Octopus and cuttlesfish are benthic, squid and nautlius are pelagic. All cephalopods are carnivorous. Prey are captured with tentacles, and moved to their powerful, chitinous beak
Label a seastar?
Gonads, rectal caecum, stomach, anus, madreporite, cardiac stomach, radial canal, ring canal, digestive gland.
What are asteroids?
Underside = oral surface, central mouth with radial digestive system. Short oesophagus opens into large stomach (fills most of central disc. Short-armed species - swallow entire prey. Long-armed species - evert stomach, partial digestion outside of body. Bivalve feeders - fatigue bivalve adductor muscles, slide stomach between valves
What are stomatapods?
Mantis shrimps, fast, efficient predators. Spearers: soft prey (e.g. fish). Clubbers: hard prey (molluscs, crustaceans). Complex behaviour (including monogamy in some spp). Extraordinary colour vision.
