Marine life is everywhere in the ocean, and although that sandy bottom may seem barren at first glance, there is a bustling community of sea creatures in the substrate. Some creatures spend their entire lives within the sandy or rocky bottoms of the sea, while others use it for just portions of their lives or opportunistically. Let’s take a look at just five forms of marine life that can be found in the substrate layer of the sea.
Garden Eel
Garden eels are so named for their quirky behavior that results in the appearance of long grasses or stems growing in a garden. Found throughout the Indo-Pacific, these members of the conger eel family live in groups, burrowing into the substrate and slowly venturing their heads out to catch passing zooplankton. They are notoriously shy, retreating quickly back into their burrows at the slightest sign of a threat.
Blenny
Measuring an average of just a few inches in length, the blenny is a reclusive species that burrows into sandy substrates, protruding its head out of the burrow to feed on a range of available food, from dead plant and animal matter to living plants and marine life smaller than itself. Blennies aren’t partial to substrate however, as they are just as happy occupying the crevices within a reef or the abandoned shell of a mollusk.
Flounder
The flounder is a flatfish species, and one of the more clever sea creatures in the substrate. Its skin is typically mottled, helping to camouflage it against sandy ocean floor, and it can dig down into the substrate to conceal itself partially or completely, ambushing prey like crustaceans, small fish, and fish spawn who have no idea that a predator is laying in wait.
Tube Worm
Tube worms are some of the more common sea creatures in the substrate, and make their living by burying their tails into the substrate and secreting minerals around the body to form a tube. While the substrate keeps them anchored, the tube protects their delicate bodies and provides an easy place to retreat when threats are sensed. When feeding, the tube worm emerges from the tube and extends its bristles, which catch plankton floating by in the water column.
Tunicate
Tunicates are delightful sea creatures in the substrate, displaying many different shapes and colors, depending on the species. Similarly to tube worms, tunicates attach themselves to the substrate and create their “tunic” from proteins and carbohydrates to protect their organs and filter sea water to extract nutrients they need to survive.
