Tide Pools

Intertidal Marine Vertebrates

Many classes of vertebrates (Phylum Chordata, Subphylum Vertebrata) also visit the intertidal zone. These animals all have a backbone (spinal column).

Class Osteichthyes (Bony Fishes)

Fishes in this class share the following characteristics:

  • scales
  • paired fins
  • gills - with a single pair of gill openings - to extract dissolved oxygen from water
  • jaw
  • paired nostrils
  • endoskeleton made of bone
  • Find out more about bony fishes in the Bony Fish InfoBook.

Some small fishes are adapted to the tide pool environment.

  • tide pool sculpin
    • Tide pool sculpins use their pectoral and pelvic fins to scoot along the bottoms of tide pools. They typically occupy the same pool each time the tide goes out and can breathe air when the oxygen gets low in a tide pool. Oligocottus maculosus is a common species of tide pool sculpin inhabiting the Pacific coast from The Sea of Okhotsk, Russia to Southern California. Other sculpin species inhabit tide pools of other regions.
  • opaleye (Girella nigricans)
    • The opaleye is an oval-shaped, olive-colored fish with iridescent blue eyes and one to three light dots on each side, just beneath the base of the dorsal fin. In their first and second year, opaleyes inhabit tide pools and are able to breathe air—an important adaptation in the oxygen depleted waters of shallow tide pools. They often return to the same tide pools whenever the tide retreats. Opaleyes range from Oregon to southern California.
  • northern clingfish (Gobiesox maeandricus)
    • This elongate fish has pelvic fins modified into a suction disc that enable it to cling tightly to the undersides of rocks in shallow tide pools. This species occupies intertidal and subtidal waters from southeastern Alaska to Baja California, Mexico.
  • monkeyface eel/prickleback (Cebidichthyes violaceus)
    • Although elongate in appearance, the monkeyface eel is actually a prickleback instead of an eel. It has a lumpy-ridged head with large lips. Adults can reach lengths of 0.76 m (2.5 ft.) making these the largest fish spotted in eastern Pacific intertidal zones. They slither, swim, and hide among crevices and rocks of intertidal and subtidal zones to depths of 24.4 m (80 ft.) and range from Oregon to Baja California, Mexico. Individual monkeyface eels usually remain within a home range of about 4.6 m (15 ft.). They can breathe air and survive out of water in moist areas for at least 35 hours.


Class Chondrichthyes (Cartilaginous Fishes)

This Class includes fishes with skeletons made of cartilage instead of bone. To learn more about sharks, rays, and other cartilaginous fishes visit the Sharks and Rays InfoBook.

  • epaulette shark (Hemiscyllium ocellatum)
    • The epaulette shark frequently inhabits tide pools on the shores of the western South Pacific Ocean, New Guinea, and Australia. It uses its pectoral and pelvic fins to crawl around the bottom of shallow water areas.


Class Aves

Class Aves includes all birds. Birds have an outer covering of feathers, are endothermic (warm-blooded), breathe air, have front limbs modified into wings, and lay eggs. Many bird species rely on intertidal habitats as places to rest or hunt for food.

  • gulls/seagulls (Larus spp.)
    • Gulls are medium to large, stout, long-winged sea birds in the Family Laridae. Like other members of this bird family, gulls have feet with three webbed toes. Most adult gulls are gray and white and some have black markings on the head or wing regions. Gulls of the Larus genus are widespread and abundant at many coastal and even inland areas. Gulls are omnivores and will hunt and scavenge for food. Some gulls use their sturdy bills to pry mussels and other shellfish off rocks in the intertidal zones, then fly up high to drop their prey onto rocks to crack open the shells and gain access to the meat inside.
  • American oystercatcher (Haematopus palliatus) and black oystercatcher (Haematopus bachmani)
    • These shorebirds have long, pink legs and straight, red-orange bills. The black oystercatcher's plumage is completely black while American oystercatchers have white bellies and white wing and tail patches. Black oystercatchers range along rocky coasts from the Aleutian Islands and along the North America's Pacific coast to Baja California, Mexico. The American oystercatcher inhabits coastlines from western Mexico to Chile and from Cape Cod to Argentina. An oystercatcher's bill is laterally compressed with a chisel-like tip to help the oystercatcher forage for food—either to pry limpets, chitons, and barnacles off the rocks or to open the shells of mussels or other bivalves.
  • ruddy turnstone (Arenaria interpres) and black turnstone (Arenaria melanocephala)
    • Turnstones are fairly small shorebirds with plump bodies, short legs, and relatively short and slightly upturned bills. Ruddy turnstones have a worldwide distribution on rocky coasts while black turnstones inhabit Pacific Coast rocky shores. Turnstones use their bills to turn over small rocks, seaweed, and shells while foraging. The black turnstone often hunts in the splash zone by using its bill to force open acorn barnacle shells.


Class Mammalia

Mammals are endothermic, breathe air, have hair or fur, bear live young, and females nurse their young with milk. Marine mammals live in or rely upon the marine environment. Some seals regularly haul-out (come out of water onto land) within the intertidal zones.

  • harbor seal (Phoca vitulina)
    • This common seal of the subarctic to temperate coastal regions of the northern hemisphere often hauls out of the water to rest on intertidal rocks. For more information on harbor seals visit the Harbor Seal InfoBook.