Lecture 12 Feeding

Question 1

Carnivorous fish prey (5)

Answer 1

zooplankton
benthic invertebrates
larval/juvenile/adult fish
mammals (seals, sea lions, etc)
birds

Question 2

predation tactics (5)

Answer 2

direct/herd prey into vulnerable site such as a shoreline, surface, or seafloor
ambush
stalk
lunge
filter feeding

Question 3

Cookie cutter shark mouth (3)

Answer 3

specialized feeding morphology
* small, erect teeth - upper
* large triangular teeth - lower
* attaches with suctorial lips

Question 4

cookie cutter shark feeding (2)

Answer 4

spins to cut out a cookie-shaped plug of flesh of larger prey
bioluminescent ventrally, with dark dorsal and collar makes the shark appear as a fish from bellow allowing it to ambush “hopeful” predators (counter-illumination pattern)

Question 5

Herbivorous fish (2)

Answer 5

rare, though 10-20% of species in tropical
ecosystems are herbivores
few if any fish are lifelong herbivores since zooplankton common in diet of larval & juvenile fishes

Question 6

feeding modes of herbivorous fish (4)

Answer 6

browsers (algae & vascular plants)
filter feeder (phytoplankton)
scrapers (diatoms & algae on rocks)
fruitivore (fruit falling in water)

Question 7

omnivores

Answer 7

most fish are omnivores to some degree, some fish are more generalists such as carp

Question 8

stable isotope analysis (5)

Answer 8

-can provide insight into trophic levels by comparing stable isotope ratios
-tissue ratios are similar to the uptake (environment) early on but:
-Carbon is built up through the anabolic process of tissue building, because terrestrial plants have less carbon than phytoplankton, primary producer for environment can be inferred
-Catabolic processes involving nitrogen favor the lighter isotope and heavier ones (such as N15) build up over trophic levels
-can empirically estimate trophic level based off difference in N15 of primary producers and examined organism

Question 9

Patterns of fish growth (3)

Answer 9

-generally, fish continue to grow their entire lives
-the idea growth pattern is sigmoid in shape, with fast initial growth that gradually slows down approaching a plateau
-in reality “stanzas” are more likely, where growth stops when the fish is stressed (winter, spawning, low food, migrations, low o2, wrong pH)