There is an amazing coral reef ecosystem that surrounds the Hawaiian islands. It supports 25 percent of all the known marine species, which includes fish, plants, and invertebrates.
Did you know that coral reefs are not plants but are made up of thousands of miniature animals called polyps? A polyp is an invertebrate that’s similar to jellyfish, with a body like a sac and a mouth that has stinging tentacles that come out at night when they feed. Coral polyps, which grow less than one inch per year, use calcium carbonate from ocean water to construct their protective limestone skeletons. There are about 50 species of coral in Hawai‘i, about 20 percent of them endemic to the Islands.
Here is some of the other marine life you may see within Hawaiian waters. You can occasionally see some of them from Hawaii Tropical Botanical Garden, which extends to the ocean at Onomea Bay.
- Honu (Chelonia mydas). The green sea turtle, whose numbers got very low, is protected by state and federal law as well as the Endangered Species Act, and all that protection is working. It’s not uncommon these days to see a honu when you’re snorkeling or swimming, or find one resting on a Hawai‘i beach, such as Punalu‘u black sand beach in Ka‘u. Honu are the largest of the hard-shelled sea turtles. A typical adult is three to four feet long, weighs 300 to 350 pounds, and probably lives to at least age 60 or 70. They primarily eat algae and seagrasses, although they sometimes also forage on sponges and other invertebrates. Never touch or approach a honu. If you see a sea turtle with an injury, such as an open wound or one that is entangled in rope or net, or witness illegal behavior around a honu, report it right away to the National Oceanic and Atmospheric Administration (NOAA) hotline at 888 256-9840 or to the Department of Land and Natural Resources at 808-643-DLNR (3567).
- Nai‘a, or Hawaiian spinner dolphins (Stenella longirostris), leap up to three meters high out of the ocean and spin. They live in Hawaiian waters year-round, resting in calm, shallow bays and lagoons during the day and foraging for fish, shrimp, and squid at night. There is an estimated 1-2,000 nai‘a off Hawaii Island. They are dark on their backs, with a light gray band on their sides, and a white underbelly. Nai‘a are protected under the Marine Mammal Protection Act, and it’s recommended you stay 150 feet (50 yards) away from them.
- Koholā, or humpback whales (Negaptera novaeangliae), spend summers off of Alaska. Every winter, around 10,000 of them swim almost non-stop for six or eight weeks until they reach warmer waters off Hawai‘i, where they breed and nurse their calves. Mother whales with nursing calves are generally the first to arrive, followed by young and newly-weaned whales. Adult males arrive next, and then pregnant females, who continue feeding in Alaska up until the last minute. You sometimes see humpbacks in nearshore Hawai‘i waters, including from the shore at the bottom of Hawaii Tropical Botanical Garden. They spout, breach, and give tail slaps during whale season, which is between November through May. Humpbacks are an endangered species protected by federal and state regulations.
- Monk seals (Monachus schauinslandi) are the most endangered seals in the U.S. They are protected under the Endangered Species Act, the Marine Mammal Protection Act, and state wildlife laws. There are only about 1,400 still living, most of them in the northwestern Hawaiian Islands. In the main Hawaiian Islands, there are only about 300. Their Hawaiian name ilio-holo-i-ka-uaua translates to “dog that runs in rough water.” You occasionally see one resting on a Hawai‘i Island beach or coastal rock. Never approach a monk seal, and keep pets leashed and away.
- Fish. About 20 percent of the fish in Hawai‘i are endemic—unique to Hawai‘i and not found anywhere else. An exception is the state fish, called humuhumunukunukuapua‘a (or Picasso triggerfish; also Rhinecanthus rectangulus). It’s a tropical reef trigger fish you may see when snorkeling off the Kona coast. The Hawaiian name means “Fish with a snout like a pig.”
- Invertebrates are animals without a backbone such as lobster, crab, octopus, sea urchins, shrimps, snails, and sponges. Coral is also an invertebrate. Hawai‘i’s reefs have fewer invertebrate species than some locations, but about 20 percent of its invertebrates exists only in Hawai‘i.
What can you do to help preserve Hawai‘i’s marine life? Leave sand and rocks where they lie. Don’t litter, and pick up any trash you see at the beach so it doesn’t go into the ocean and threaten marine life. Wear a flotation device when you snorkel, so you don’t step on or touch coral for balance. Do not feed wildlife, and keep your distance from green sea turtles and monk seals.