This is a video sidebar to a longer feature on “How Fish Feed.” Two minutes in length, it shows four types of fish bottomfeeding techniques to find and capture small crustaceans, mollusks and other invertebrates buried in the sand flats surrounding reefs.
WHEN YOU’RE TALKING ABOUT LOAN SHARKS AND SHADY LAWYERS, “bottom-feeding” is a disparaging term. But for lots of fish and other reef denizens, it’s a productive way of life.
We may see a sandy seafloor as something like a desert, devoid of the dazzling creatures that we dive to see in lush oasis-like reefs. But actually, the sand is crammed with life – worms, crustaceans like copepods and crabs, clams and other mollusks, bacteria and decaying organic matter. They sound disgusting, but to bottom feeders they’re delectable edibles. Well, at least they’re edibles.
Some fishes thrive on them, using diverse strategies and strong jaws to find and eat them. Here are how four fish groups earn their livings:
• FISH BOTTOMFEEDING STRATEGIES 1: STREAMING AWAY SAND
Trunkfishes, hogfishes and triggerfishes are among species that puff jets of water into the bottom to reveal juicy morsels – fracking, fish-style.
• FISH BOTTOMFEEDING STRATEGIES 2: STIRRING AWAY SAND
Stingrays have a different approach. Using senses of smell, vision, hearing and electroreception to detect the presence of prey, they flap their wings – their broad pectoral fins – to stir up the sand and uncover food. Then they use their powerful jaws to crush and grind up shells. They also have lots of fishy friend who follow them around hoping for easy meals from the rays’ leavings.
• FISH BOTTOMFEEDING STRATEGIES 3: PROBING THE SAND
Watching goatfish, you’d be excused for assuming their characteristic barbels are digging tools. They’re not. They’re chemical sensory probes the goatfish use to search out the scent clues of worms, clams, crustaceans or whatever hidden in there. When they detect something edible, they plunge their snouts right into the sediment, ingesting sand along with the aforementioned copepods or worms or whatever. They discharge the sand through their gill covers.
• FISH BOTTOMFEEDING STRATEGIES 4: JUST GOING FOR IT
Eagle rays, although pelagic swimmers, are bottomfeeders that do pretty much the same thing. Rays don’t have barbels but they use senses of smell, vision, hearing and electroreception to detect prey. They dig into the sand with shovel-shaped snouts crush the shells of the copepods, crabs and little mollusks they find with hardened jaws.
PRINCIPAL SOURCES: Marine Biology, Peter Castro, Michael Huber; Reef Fish Behavior, Ned DeLoach; Watching Fishes, Roberta Wilson and James Q. Wilson; Reef Fish Identification Florida, Caribbean, Bahamas, Paul Humann, Ned DeLoach; Reef Fish Identification, Tropical Pacific, Gerald Allen, Roger Steene, Paul Humann, Ned DeLoach; Marine Life, Caribbean, Bahamas, Florida, Marty Snyderman & Clay Wiseman; Mouth Types, Surgeonfishes, Gobies, et.al., Florida Museum/University of Florida Museum of Natural History; Fish Mouth Types and Their Uses, The Spruce, Pets; Suction, Ram, and Biting: Deviations and Limitations to the Capture of Aquatic Prey, Integrative and Comparative Biology; Goatfishes, Waikiki Aquarium; Flounders, Grunts, Spotted Eagle Rays, et.al., Wikipedia; How Fishes Feed: For One Thing They Suck It Up, Poseidon’s Web – Explain the Reef!