Benthic invertebrates Flashcards
What are benthic invertebrates?
Animals associated with the seabed, including epibenthic (on the surface or shallowly buried) and infaunal (within sediments) species
Play diverse roles in marine ecosystems
What are the main feeding modes of benthic invertebrates?
Carnivory, herbivory, deposit feeding, and filter feeding
Fedding strategies linked to morphology and habitat
What characterizes cephalopod carnivory?
Octopuses and cuttlefish are benthic, while squids and nautiluses are pelagic
All use tentacles and chitinous beak to subdue prey
How do asteroids (sea stars) feed?
Short-armed species swallow prey; long-armed species evert their stomach to digest externally
May fatigue bivalve muscles to access soft tissue
What feeding adaptations are seen in mantis shrimps (Stomatopods)?
Spearers hunt soft prey, clubbers crush hard prey
Show complex behaviour like monogamy and colour vision
What distinguishes decapod crustaceans?
ive pairs of pereopods, often with the first pair modified into claws (chelipeds)
Crabs, lobsters, shrimp etc
What is the radula and which organisms use it?
A chitinous, toothed ribbon in molluscs (e.g., gastropods) used for scraping algae
Teeth continually replaced
What structure do echinoids use to feed?
Aristotle’s lantern—a set of five rigid teeth around a central jaw on the oral surface
What is the feeding strategy of deposit feeders?
They ingest sediments and digest the organic matter
Which crustaceans are mainly marine detrivores or scavengers?
Isopods and amphipods
How do filter feeders obtain food?
By capturing suspended particles, either passively or by creating currents
Sponges, corals, bivalves, tunicates etc
What is unique about adult barnacle morphology?
They’re essentially shrimp cemented head-first to surfaces, with protective plates
Order Sessilia = acorn barnacles; Pedunculata = goose barnacles
How are polychaetes classified and what do some sedentary types do?
nto errantia (mobile) and Sedentaria (tube-dwellers); some sedentary species build reefs and use head fans to feed
Serpulids and sabellariids
What are brittle star beds and where are they found?
Dense aggregations of brittle stars (e.g., Ophiothrix fragilis) covering areas >1000/m²
British waters and beyond
What determines the feeding strategy of benthic invertebrates?
Prey availability and environmental conditions
Species adapt to efficiently exploit local resources
Name common decapods found in British intertidal zones
Prawns, brown shrimp, velvet swimming crab, shore crab, brown crab, broad-clawed porcelain crab
How can you distinguish male and female crabs or lobsters?
Crabs: males have a narrow triangular abdomen; females have broader curved ones
Lobsters: male pleopods are hard and calcified; female pleopods are soft and feathery
