Diving in Hawaii means you are assured of seeing species you have not seen before. This is because Hawaii has a high percentage of species that are endemic, meaning they are found only here. Currently 23% of the fish, 20% of the mollusks, 18% of the algae (OK, so we won't elaborate on the algae) and about 20% of the corals are considered endemic. These numbers are constantly changing as species thought to be found only in Hawaii are discovered elsewhere, and as opinions vary concerning when a population is different enough to be considered a separate species. Although these endemic percentages might not sound high, they are high by marine animal standards. Here is what you are in store for:

Fish

According to Dr. Jack Randall, 23% of the fish species in Hawaii are unique to the Hawaiian Islands. This can be not-so-exciting as in the case of the Hawaiian Lionfish, because a very similar species, the Spotfin Lionfish, is found in Indonesia and other Indo-Pacific areas.

Or it can be very exciting as in the case of the chubby little Bandit Angelfish, which has no known relative anywhere in the world. This means that the species from which it evolved no longer even exists!

Endemic species result when the larvae of a particular species arrive in Hawaii and then tens or hundreds of thousands of years pass without another infusion of such larvae. During that time these individuals have only each other to breed with. Their gene pool changes over time, influenced by the local conditions, and eventually they become different from the original ancestor species.

About 9 years ago we witnessed one step in this process. Up until July of 1992 only two species of sergeant were known from Hawaii - the Blackspot Sergeant and the Hawaiian Sergeant. Then one day at Molokini we noticed a third species, the Indo-Pacific Sergeant, a species never

previously seen in Hawaii. We were witness to a group of larvae of a particular species that had run the gauntlet of time and adverse conditions and accidentally arrived in the Hawaiian Islands. It is thought that the Hawaiian Sergeant evolved from the Indo-Pacific Sergeant, but they have both changed so much they are no longer able to interbreed.

Mollusks

Dr. Alison Kay of the University of Hawaii estimates from the current number of marine mollusk species found here that a new marine mollusk may have successfully colonized the Hawaiian Islands on average only once every 13,000 years! Of course, the majority of species capable of colonizing Hawaii would have done so as soon as the habitat became available, with species less capable of colonizing trickling in more by chance later on.

Hawaii naturalist Cory Pittman estimates that there are roughly 2,000 species of marine mollusks in Hawaiian waters. Most authors consider 20% of Hawaiian marine mollusk species to be endemic, some beautiful examples being the Burnt Murex and the Waxy Cowrie.

Another characteristic of Hawaiian seashells is that some, such as the Tiger Cowrie, reach much greater size here than anyplace in the world. A Tiger Cowrie from Hawaii, even though it is not different enough to be considered a separate species, is easy to differentiate from its Indo-Pacific brothers and sisters.

Tiger Cowrie (Cypraea tigris)

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