The ocean floor may seem like a barren wasteland, but it is actually teeming with life. Many fish have adapted incredible abilities to burrow and hide in the sandy seabed. If you’ve ever wondered what fish can disappear into the sand, you’ve come to the right place.
Here’s a quick answer before we dive deeper: Fish like stingrays, flounders, crocodilefish, and sand lances are able to quickly bury themselves in sand to hide from predators or ambush prey.
Fish That Can Completely Bury Themselves in Sand
Stingrays
Stingrays are well-known for their ability to conceal themselves in sand and sediment at the bottom of the ocean. Their flat, diamond-shaped bodies allow them to easily cover themselves when resting or hiding from predators.
Some species like the Atlantic stingray even have skin flaps along their pectoral fins that can further obscure their outline in the sand.
When buried, only the stingray’s eyes, nostrils, and respiratory holes may remain visible. Their eyes protrude slightly to provide vision. The underside of a buried stingray also remains exposed to allow water flow for respiration.
They can stay concealed this way for hours, camouflaging almost flawlessly on the seafloor.
Flounders
Flounders are lateral flatfish that use their flat bodies to their advantage. They settle on the bottom resting on one side. By undulating, they can bury themselves until only their eyes remain above the sediment. Their side-facing eyes provide an unhindered view even when covered by sand.
Like stingrays, flounders can match the ocean bottom’s color and texture, rendering them practically invisible to predators. Species like the winter flounder can shift between brown and gray to blend into sandy or muddy bottoms when they settle and bury.
Crocodilefish
The crocodilefish has a uniquely shaped head and body well-designed for hiding in the sand. Its flattened head and body allow it to easily half-bury itself, disguised as just a part of the sediment bed.
With its variable coloration and ability to disrupt its outline, it can be incredibly challenging to spot.
Its proportionally long dorsal and anal fins can also assist to conceal its body shape. Crocodilefish often orient themselves so they are facing into the current. That way, prey and food particles get washed straight into their large mouths.
So they hide in wait buried in the sand until it’s time to strike.
Fish That Partially Bury Themselves in Sand
Sand Lances
Sand lances, also known as sand eels or launces, are elongated fish in the Ammodytes genus that burrow in wet sand for protection and concealment (Animal Diversity Web). They swim in large schools close to shorelines and dive head first to bury themselves with a wiggling motion, leaving only their eyes exposed to spot predators.
Sand lances have scaleless skin to ease friction when burrowing. Their streamlined bodies and rounded snouts are perfectly adapted for rapidly tunneling tail-first back into sand if danger approaches.
There are around 6 species of sand lances that populate ocean floors across the globe. For example, the Northern sand lance ranges along the eastern coast of the North Atlantic Ocean, while the Double-ended sand lance is found mainly in the Pacific Ocean (Encyclopedia Britannica).
Though small, typically under 12 inches long, sand lances form a vital link in marine food chains. They feed on plankton and small crustaceans and in turn are preyed on by larger fish, seabirds, seals, and cetaceans.
Solefish
Solefish like European soles, Pacific soles, and even halibuts partially bury themselves on the ocean floor awaiting prey. They have oval flattened bodies that allow them to conceal themselves under a thin layer of sand, with eyes located on one side that remain vigilant for prey like worms, mollusks, and crustaceans (Animals Network).
Their technique involves first settling to the bottom, then undulating to sink slightly into the substrate. Finally, solefish use their fringed fins to sweep sand over their bodies.
These cunning predators often position themselves facing currents to surprise exposed prey tumbling downstream. Some species can dart out in the blink of an eye to vacuum food into their mouths. The European sole in particular has adapted coloration to seamlessly blend with sandy or muddy bottoms.
They can grow over 3 feet long and may live for over 50 years.
Skates
Skates like cownose rays and guitarfishes are elasmobranchs related to sharks that partially conceal themselves on the seafloor. They have heavy flattened bodies suited to resting on the bottom. Distinctively, skates also have greatly enlarged pectoral fins that resemble wings (National Geographic).
As they settle down, their undulations create shallow depressions that get filled in by drifting sediments.
Sometimes only their eyes peek out to spot mollusks, worms, crustaceans and small fish. When prey passes by, skates explode with a burst of speed thanks to their powerful wing-like fins. They bash prey with their blunt snouts or scrape food into their ventral mouths.
The cownose ray is especially adapted for rooting out bottom-dwelling shellfish. Some species may migrate long distances along coastlines in large schools, while others are solitary hunters.
How Do Fish Burrow in Sand?
Many species of fish have evolved amazing abilities to burrow and tunnel through sand or gravel. Here are some of the key adaptations that allow fish to move effectively through sandy substrates.
Specialized Body Shapes
Certain fish have long, narrow, cylindrical bodies that can slip through the spaces between sand grains with ease. Examples include eels, sand lances, and worm eels. Their smooth, slippery skin also helps them slide through sand without much resistance or abrasion.
Undulating Movements
Anguilliform swimmers like eels propel themselves through sand via lateral undulations of their bodies. This snakes like motion pushes the sand grains aside to make space for the fish to move forward. Some species can even swim backwards!
The undulations may involve the whole body or just the posterior region.
Sand-Expelling Organs
Many burrowers have special adaptations to actively eject sand as they tunnel. For example:
- Butterfly rays have greatly enlarged gill slits to expel sand.
- Stargazers have a short, muscular tube above their gills that pumps out sand.
- Sand lances have a protruding snout and gill rakers that create currents to flush out sand.
Other specializations like an upward pointing mouth, sensory tentacles, and modified fins also assist fish to navigate and maintain their burrows below sandy bottoms. Clearly, burrowing fish display a remarkable array of morphological and behavioral strategies for subsurface living.
Why Do Fish Bury Themselves in Sand?
Camouflage from Predators
Many species of fish bury themselves in sand to avoid detection from predators. By hiding in the sand, they can seamlessly blend into the ocean floor, making it very difficult for predators to spot them (1). This form of camouflage is highly effective as a defensive strategy.
For example, stingrays often cover their bodies with sand, leaving only their eyes poking out to monitor for danger. Pretty ingenious if you ask me!
Ambush Predation
While some fish bury for protection, others do it to attack unsuspecting prey. Fish like stargazers burrow themselves and wait patiently for food to swim or crawl by. Then, when the moment is right, they burst out and vacuum up their meal with lightning speed. Talk about a terrifying ambush!
This feeding strategy allows them to catch far more prey than actively hunting. Pretty clever, right?
Avoid Currents
Many bottom-dwelling species lodge themselves in sand to avoid getting swept up by currents. Without burying, they would constantly have to fight to stay in place which could rapidly deplete their energy stores.
By hiding out below the sand surface, fish can enjoy calmer waters and exert less effort holding their position on the seafloor. It’s like building a sturdy anchor to avoid getting dragged away!
Resting
Finally, some fish use sand as a cozy place to rest! Species like marble sleeper gobies dig out small pits to take naps in during the day or night. Without coverage, they would feel exposed and have difficulty relaxing.
By burrowing into the sediments, fish can enjoy darkness, warmth, and privacy while catching up on some much-needed Zzz’s. It’s like making a comfy bed below the seabed!
Conclusion
As we’ve explored, a number of marine fish have evolved amazing anatomical adaptations to bury themselves in sand. Flounders, stingrays, and crocodilefish can conceal their entire bodies, while fish like lances and solefish partially submerge.
By burrowing in the seabed, fish can hide from danger, sneak up on prey, rest, and avoid currents.
The next time you’re walking along the beach, remember the incredible diversity of life hidden just below the water’s surface. Fish have secrets in the sand!
