Meet the Kelp Forest Species

Pacific giant kelp is the foundation of a diverse marine ecosystem, creating underwater forests that provide shelter and food for many coastal marine species. Giant kelp is not a plant; it has no roots, stems, or leaves — but like a plant, it produces its own food through photosynthesis. Special gas-filled bladders help each leaf-like blade float upward, exposing it to sunlight. Giant kelp anchors itself to the sea floor with a structure called a holdfast, which resembles a tangle of plant roots (though unlike plant roots, holdfasts do not absorb nutrients). Reproduction in giant kelp involves two stages: first, a mature kelp releases spores into the water, which settle on rocks and develop into microscopic male and female individuals. As these mature, they release eggs and sperm into the water for fertilization. The fertilized eggs drift with the current, eventually attaching to rocks on the ocean floor and growing into the giant kelp we see offshore.

Fun fact: Giant kelp is one of the fastest growing organisms, growing up to two feet per day, and mature kelp can reach 175 feet in length! In 1917 and 1918, San Diego harvested nearly 400,000 tons of kelp (a source of potash) annually to make explosives and gunpowder for World War Ⅰ․ Some say the Allies won the war with the help of kelp!

This variable species can be found in a variety of colors, including tan, green, brown, white, and even bright orange, adding a splash of vibrancy to the underwater landscape.

Fun fact: The breadcrumb sponge is a favorite food of the San Diego sea lemon.

The sunburst anemone is named for its striking appearance. This species is found in both the intertidal and subtidal zones. The column of its body is lined with numerous sticky bumps that catch debris, gravel, and shell fragments. It uses its stinging tentacles to feed on small invertebrates and fish, and to catch floating particles of organic material.

Fun fact: The vibrant green color of sunburst anemones found north of San Francisco is due to the presence of single-celled algae living within the tissues of these animals.

The California golden sea fan is actually a colony of thousands of clonal polyps arranged along numerous branches. Each polyp has tiny tentacles to capture food from the water. The fan-shaped structure of the colony allows for water, small organisms, and particles to flow through. Sea fans are completely dependent upon currents to bring them food, which is why they usually grow on the tops and sides of reefs, orienting their "fans" perpendicular to the current. Reproduction occurs through the release of eggs and sperm into the water, resulting in the development of larvae that disperse and settle on the seafloor.

Fun fact: California sea fans create many kinds of chemicals that have potential use in medicine as antibacterial and anticancer drugs.

The common name of this giant sea slug refers to the two long tentacles on its head region that resemble rabbit ears. Sea hares feed mainly on various species of red algae. This species is hermaphroditic, so when two sea hares mate, both fertilize each other. After mating, each individual lays long, gelatinous pink strings of eggs clumped in a spaghetti-like mass. Each egg mass may hold over a million developing embryos that hatch after 12 days, releasing planktonic larvae.

Fun fact: sea hares release ink when threatened or disturbed. The ink smells like cedar wood, and its vivid purple color is derived from pigments in the red algae these animals consume.

The San Diego sea lemon is a vibrant yellow-orange sea slug. It feeds on sponges and other organic material that it scrapes off rocks with a toothed feeding structure called a radula. This slug has exposed frilly gills clustered on its back end to extract oxygen from the water. Sea slugs are called nudibranchs (naked gills) for this reason. Sea lemons are simultaneous hermaphrodites, meaning they have both male and female reproductive organs. During mating, two sea lemons exchange sperm, and each individual then lays a ribbon-like mass of eggs that resembles a lemon peel.

Fun fact: The San Diego sea lemon actually has a distinct citrus-like scent!.

The wavy turban snail, named for the curvy edges of its shell, has a herbivorous diet, and feeds primarily on various species of algae and kelp. As these snails crawl over their rocky habitat, they use their rough, toothed radula to scrape and consume algae. Reproduction in these snails involves internal fertilization. Females lay egg capsules attached to rocks or other hard surfaces. The capsules contain multiple eggs, and the juveniles hatch from them and crawl away.

Fun fact: To protect themselves from predators, wavy turban snails withdraw their bodies into their shells and seal the opening with a calcium plate that serves as a protective "trapdoor."

The bat star is found in the rocky intertidal zone as well as subtidal areas offshore. They feed on a variety of organisms such as small invertebrates, algae, and even detritus (debris and particles of organic matter from the remains of dead animals and seaweeds). They use tube feet tipped with tiny suction cups to capture and consume their food. These scavengers play vital roles in their ecosystems by cleaning algae and decaying animal tissue from the ocean floor, recycling nutrients back into their food webs.

Fun fact: The skin of many types of sea stars is covered with delicate gill-like structures, giving them a fuzzy appearance.

The California spiny lobster is an omnivorous scavenger, feasting on a variety of foods including fish, mollusks, algae, and dead organisms on the ocean floor. Individuals can live up to 50 years in the wild. During reproduction, a female carries up to 800,000 fertilized eggs on her underside until they hatch into larvae that then drift in currents for up to 10 months. Larvae undergo 11 stages of development before settling down onto the seafloor as miniature versions of the adults.

Fun fact: Spiny lobsters can make alarm sounds to intimidate predators. They sweep their antennae back and forth, and the base of each antennae scrapes against a roughened surface on the lobster’s shell, creating a strident, rasping sound.

California's official state marine fish is the orange garibaldi. Native to the coast of California and Baja California, these pugnacious fish feed on small invertebrates such as crustaceans, worms, and mollusks, crushing them with their powerful jaws and teeth. Garibaldis build nests in rocky areas, which they maintain and defend. During courtship, males perform elaborate dances to attract females. Once the female lays her eggs in a nest, the male carefully guards them until they hatch.

Fun fact: To protect their nests, garibaldis have been known to attack intruders, including snorkelers and divers,

This sponge feeds by creating a water current with special cells that bring small particles of food from the surrounding water into the sponge’s body. This process is called filter feeding. Sponges reproduce through both sexual and asexual methods. Sponges release sperm cells, which enter into another sponge to fertilize an egg. The developing sponge larvae is ejected from the parent, and floats away to later attach onto a rocky surface. An asexual method of reproduction is called fragmentation, when pieces of a sponge break off and regrow into clones of their parent.

Fun fact: The brilliant blue color of this sponge is due to blue-green bacteria living within the sponge.

This species is unique in that it actively bores into the shells of clams and oysters by secreting chemicals that dissolve the shell’s calcium materials. This creates tunnels and chambers where the sponge lives. Consequently, these sponges have been known to cause significant damage to commercially farmed shellfish populations, but in the wild, boring sponges are a part of the natural recycling process in marine environments.

This species favors places where the current is strong, but is also found on docks and pier pilings. The column of the plumose anemone can be white, brick red, or brown. In the process of sexual reproduction, eggs and sperm are released into the water and after fertilization, anemone larvae develop while floating in the water as plankton, then settle to the seafloor to develop into the adult form. But this anemone can also increase its numbers by a type of asexual reproduction called binary fission, by splitting in half and growing into two organisms.

Fun fact: The plumose anemone is a sequential hermaphrodite – it starts life as a male and changes to become female as it gets older.

Strawberry anemones are named for the bright red-orange coloration of their polyps, which grow together as a colony over hard substrates. Like other sea anemones, the strawberry anemone has tentacles bearing specialized structures called nematocysts which act like microscopic harpoons to inject toxin into the tissues of its prey. The tentacles are extended at night to capture small marine organisms such as plankton and tiny crustaceans.

Fun fact: In addition to sexual reproduction through spawning, strawberry anemones also undergo asexual reproduction through a process called budding, where new clonal “babies” grow from the base of a parent anemone.

This eye-catching blue/gold sea slug mainly feeds on sponges. Like other types of sea slugs, this species is hermaphroditic—both male and female reproductive organs are found in each individual animal. These nudibranchs are more active at night, coming out to feed. During the day, they may hide in crevices and under rocks.

Fun fact: These slugs are not affected by the distasteful chemicals produced by the sponges they eat, but instead they isolate the chemicals and store them in glands lining their body surface to protect themselves! This, in combination with the slug’s bright color patterns, apparently causes fish predators to learn that the slugs taste terrible, and aren't worth eating.

The pink abalone (Haliotis corrugata, upper specimen) and green abalone (Haliotis refulgens, lower specimen) are flat-shelled mollusks and herbivorous grazers, feeding on a variety of algae and seaweed. Their grazing can influence the composition of underwater vegetation. For reproduction, these animals spawn: males release sperm into the water, fertilizing eggs released by females. The fertilized eggs develop into larvae that float in the water column for up to several weeks before settling on suitable substrates to grow into young abalones. Abalones can live to 30 years or more.

Fun fact: Almost all of the world's abalone sold commercially is raised in saltwater tanks onshore or in suspended cages in the ocean. It takes about three to four years for young abalone to grow to the length of a chicken egg.

The smooth turban snail is a common mollusk in Southern California kelp forests. Like the wavy turban snails, they are also herbivores, preferring giant kelp. These snails crawl up the kelp at dusk to dine on its blades and then descend at dawn. Smaller snails often crawl into the kelp’s holdfast to hide during the day.

Fun fact: The shell of a smooth turban snail has a structure called an umbilicus on its underside, and it looks like a green belly button.

Found along the Pacific coast from Alaska to Baja California, the Pacific knobby sea star is one of the largest sea stars in the world. Its vibrant colors and large size make it the  “rock star” of the coastal zone. They use their numerous, suction-cup like tube feet to pry open the shells of mussels and clams and then evert their stomachs outside of their bodies and onto the soft tissue of their prey, digesting and absorbing it. Sea stars have separate sexes, each releasing either eggs and sperm into the water for external fertilization.

Fun fact: Sea stars have an incredible ability to regenerate lost arms, and the tip of each arm bears a light-detecting organ that’s like a primitive eye!

The California moray eel has a varied diet that includes small fish, crustaceans, octopus, and even other eels. It is primarily a nocturnal hunter with an incredible sense of smell that lets it detect prey lurking in crevices, which it then captures and subdues with its powerful jaws and sharp teeth. California moray eels can reach a total length of 1.5 meters (5 feet).

Fun fact: Unlike most fish, the moray lacks gill covers. Most fish extract oxygen from seawater by opening and closing their gill covers, forcing seawater over their gills. But a moray must constantly open and close its mouth to circulate water over its gills, which gives it a menacing appearance.