Oahu is home to a diverse ecosystem of animals, some very unique to the island(s). This is a fairly short list in comparison to the majority that call Oahu home, but I wanted to share some insight to some of the fauna you might come across while here. Many animals are protected, including sea lions and sea turtles. Never approach a sleeping animal on the beach or sea life in the water, keep a respectable distance to allow them the freedom to eat/sleep/etc. If you love identifying animals and creatures like I do, this is an incredibly detailed and helpful site I came across: click here
Animals
of Oahu
hawaiian green sea turtle
Hawaiian green sea turtles, or honu, are native to Hawaii. They are the largest hard-shelled sea turtle in the world, reaching lengths of four feet and weights over 300 pounds! Hawaiian green sea turtles are the most common sea turtle in Hawaii.
The color of their carapace (upper shell) ranges from brown with yellow and light brown streaks to black. The color of their plastron (bottom shell) is a light yellow. As adults, honu mainly eat algae and sea grasses, which turn their fat layer green, giving them their common name.
You can spot these cool reptiles around any reefy area with algae, where they like to snack... or taking a rest on the beach. Just be sure to give them space to do as they please :)
Geckos
Another iconic animal in Hawaii is the Gecko. You can find these little cuties anywhere and everywhere, the forest, business, your home, even your car! The Polynesians brought them here about 1,500 years ago along with other plants and animals. Today, there are eight gecko species in Hawaiʻi: mourning gecko, stump-toed gecko, fox gecko, common house gecko, tokay gecko, orange-spotted day gecko, giant day gecko and gold dust day gecko. The first five are nocturnal; the other three, as their names suggest, are active during the day. An interesting article I found can be read here.
Hawaiian octopus
In Hawai'i, there are two common species of octopus, often called “squid” locally. ... Also common in Hawaiian waters is the “night octopus” or he'e-mākoko, a rusty red animal with white spots on the body and arms. Source: Waikiki Aquarium
These animals are so beautiful, and you get a deep sense of soul and humility if you get a chance to look into their eyes. They are great at hiding but can sometimes be spotted by a trained eye scuttling across the reef. This little guy was cruising off the shores of Electric beach and hung out with us for a bit, gripping onto my watch and suctioning to my hands before being placed back in a hole to hide from predators. It was like holding velvet superglue! They are very curious but will ink and shoot themselves away when they are over the interaction.
DOLPHINS
Dolphins are some of the smartest creatures out of all the Hawaiian wildlife with a unique social behavior.
I have often seen them in Waimea Bay, as well as off the North Shore beaches since that’s where they typically mate.
Spinner dolphins are the most common type you’ll spot.
To keep yourself and dolphins safe, keep a safe distance from them. It is still incredible to watch them from afar! Whether you’re exploring the open ocean on a boat tour or witnessing their acrobatics from the shore.
humpback whales
From their haunting songs to their epic migrations, these giants of the deep are so extraordinary. Whale watching in Oahu is one of the must do’s while visiting the tropical paradise.
Navigate the waters of Oahu to catch a glimpse of humpback whales during their annual migration. Whether from a whale-watching tour or a scenic coastal vantage point, people often spot whales while visiting Oahu. The peak season of whale migration in Hawaii is in the winter—usually November through February.
Jackson's chameleon
If you find yourself in a brush of Hale Koa, look up and look hard. You may be able to spot this illusive reptile, Jackson’s chameleons are a popular pet that can escape the cage and establish feral populations in Hawaiʻi. They are bright emerald green fading to a yellowish color on their undersides. Males are generally 10-12” long with a long, prehensile tail accounting for half of their length, and with three horns protruding from their forehead. Females are generally a little shorter and never grow horns. Jackson’s chameleons are solitary creatures which spend most of their time in trees. Chameleons move with a distinctive slow rocking motion. Source: Hawaii.gov
hawaiian monk seals
Seals are found on secluded beaches and coastal areas where they often seek refuge. Respectful observation is key to ensuring their well-being. Hawaiian monk seals are the rarest seal species in the world. While these wild creatures are beautiful, they shouldn’t be approached by humans. They are only found in Hawaii!
Two types of seals call Hawaii home: elephant seals and Hawaiian monk seals. You’ll find plenty of elephant seals and will know the difference due to their loud call.
Mongoose
Mongoose are an introduced species with a unique history on the island. These curious creatures have adapted to a variety of habitats.
Even though it’s non-native Hawaiian wildlife, you’ll probably see quite a few Indian mongeese. These creatures were introduced to Hawaii to lower the rat population in sugar cane fields.
Mongeese ravaged after bird and turtle eggs, being blamed for the population dip of Hawaiian crows, geese, and other birds. The long, brown body of the mongoose makes it look like a weasel.
sharks
Hawaii’s approximately 40 species of sharks are each unique in their own way. There’s no mistaking a whale or hammerhead shark, and the characteristic blunt nose and dorsal stripes of a tiger shark make it fairly easy to recognize. But do you know how to tell the difference between a smooth hammerhead and a scalloped one?
Many of the more common inshore sharks, especially those of the family Carcharhinidae, are hard to distinguish from each other. But most have some kind of characteristic, often in the form of color patterns, that help in identification, if you can get a good look at them.
The offshore sharks are less frequently seen, but most are easy to recognize if you know what to look for. An exception is the silky shark, which has no particular markings. Some of the other sharks are rarely seen, especially the deepwater species. Most people never get the chance to try and identify them.