L19 - Benthic Invertebrates Flashcards

1
Q

What are the benthic habitats?

A

Benthos, epibenthic, infauna

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2
Q

What is benthos?

A

Associated with the sea bed

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3
Q

What is epibenthic?

A

Attached to a hard substratum or rooted to a shallow depth below seabed surface

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4
Q

What are benthic invertebrate feeding modes?

A

Herbivores, carnivores, deposit feeders, filter feeders.

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4
Q

What is infauna?

A

In sediment

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5
Q

What do suspension (filter) feeders do?

A

They capture particles from water. Passive - use existing current, active generate own current

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6
Q

What are some examples of important filter feeders?

A

Bivalves, bryozoans, cirripedes, corals, holothurians, ophiuroids, polychaetes, sponges, tunicates

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7
Q

What is the class cirripedia: super order thoracica?

A

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

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8
Q

What are brittle star beds?

A

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

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9
Q

What are the two clades of Polychaetes?

A

Errantia and Sedentaria

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10
Q

What are the Sedentaria?

A

Include colonial, reef-building forms with fans of head tentacles like the serpulids and sabellariids.

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11
Q

What do deposit feeders do?

A

Ingest sediment and digest organic content. Many are also scavengers

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12
Q

What are some examples of important deposit feeders?

A

Bivalves, crustaceans, gastropods, holothurians, polychaetes

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13
Q

What are isopods and amphipods generally?

A

Mostly marine, detritivores/scavengers

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14
Q

What are Isopoda?

A

Dorso-ventrally flattened, aquatic species are benthic. Numerous deep sea spp (some get very large). Some important parisitic forms.

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15
Q

What are Amphipoda?

A

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

16
Q

What are gastropods?

A

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.

17
Q

What is aristotle’s lantern?

A

Centrally located jaw on oral surface. Surrounded by 5 rigid teeth. Named by aristotle

18
Q

Recruitment of larval urchins to removal of urchin predators (otters, lobsters) cycle?

A

Increased sea urchin density, destructive grazing, barren grounds, disease in urchins, mass urchin mortality, recruitment and re-establishment of kelp, kelp beds.

19
Q

What are examples of irregular echinoids?

A

Sand dollars (Clypeasteroida) and Heart urchins (Spatangoida)

20
Q

How do cephalopods feed?

A

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

21
Q

Label a seastar?

A

Gonads, rectal caecum, stomach, anus, madreporite, cardiac stomach, radial canal, ring canal, digestive gland.

22
Q

What are asteroids?

A

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

23
Q

What are stomatapods?

A

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.

24
Q

What are decapods?

A

Largest and most diverse group within the malacostraca. Crayfish, crabs, lobsters, prawns and shrimp. Five pairs of pereopods (decapod). First pair of pereopods usually with claws (chelae): chelipeds.

25
Q

What is foraging ecology?

A

Wide range of feeding habits and diets. Predatory and scavengers. Strategy depends on prey availability. Large invertebrates are common prey. Well adapted to particular prey.

26
Q

What are some common decapods in british rockpools?

A

Prawns (Palaemon spp), brown shrimp (Crangon crangon) burrow in fine sand, mud, velvet swimming crab (Necora puber), shore crab (Carcinus maenas), brown crab (Cancer pagurus), Broad-clawed porcelain crab (Porcellana platycheles)