Located about 2300 miles (3680 km) from the nearest continental shore, the Hawaiian Islands</b> are the most isolated group of islands on the planet. The plant and animal life of the Hawaiian archipelago is the result of early, very infrequent colonizations of arriving species and the slow evolution of those speciesâ€"in isolation from the rest of the world's flora and faunaâ€"over a period of at least 5 millions years. As a consequence, Hawai'i is home to a large number of endemic species. The radiation of species described by Charles Darwin in the Galapagos Islands which was critical to the formulation of his Theory of Evolution is far exceeded in the more isolated Hawaiian Islands.
The relatively short time that the existing main islands of the archipelago have been above the surface of the ocean (less than 10 million years) is only a fraction of time span over which biological colonization and evolution have occurred in the archipelago. High, volcanic islands have existed in the Pacific far longer, extending in a chain to the northwest; these once mountainous islands are now reduced to submerged banks and coral atolls. Midway Atoll, for example, formed as a volcanic island some 28 million years ago. Kure Atoll, a little further to the northwest, is near the Darwin Pointâ€"defined as waters of a temperature that allows coral reef development to just keep up with isostatic sinking. And extending back in time before Kure, an even older chain of islands spreads northward nearly to the Aleutian Islands; these former islands, all north of the Darwin Point, are now completely submerged as the Emperor Seamounts.
The islands are well known for the environmental diversity that occurs on high mountains within a trade winds field. On a single island, the climate can differ around the coast from dry tropical (< 20 in or 500Â mm annual rainfall) to wet tropical; and up the slopes from tropical rainforest (> 200 in or 5000Â mm per year) through a temperate climate into alpine conditions of cold and dry climate. The rainy climate impacts soil development, which largely determines ground permeability, which affects the distribution of streams, wetlands, and wet places.
The distance and remoteness of the Hawaiian archipelago is a biological filter. Seeds or spores attached to a lost migrating bird's feather or an insect falling out of the high winds found a place to survive in the islands and whatever else was needed to reproduce. The narrowing of the gene pool meant that at the very beginning, the population of a colonizing species was a bit different from that of the remove, contributing population.
Island formation
Throughout time, the Hawaiian Islands formed linearly from north-west to the south-east. A study was conducted to determine the approximate ages of the Hawaiian Islands using Kâ€"Ar dating dating of the oldest found igneous rocks from each island. Kauai was determined to be about 5.1 million years old, Oahu about 3.7 million years old and the youngest island of Hawaii about 0.43 million years old. By determining the maximum age of the islands, inferences could be made about the maximum possible age of organisms inhabiting the island. The newly formed islands were able to accommodate growing populations, while the new environments were causing high rates of new adaptations.
Human arrival
Human contact, first by Polynesians and later by Europeans, has had a significant impact. Both the Polynesians and Europeans cleared native forests and introduced non-indigenous species for agriculture (or by accident), driving many endemic species to extinction. Fossil finds in caves, lava tubes, and sand dunes have revealed an avifauna that once had an endemic eagle, two raven-size crows, several bird-eating owls, and giant ducks known as moa-nalos.
Today, many of the remaining endemic species of plants and animals in the Hawaiian Islands are considered endangered, and some critically so. Plant species are particularly at risk: out of a total of 2,690 plant species, 946 are non-indigenous with 800 of the native species listed as endangered.
A list of endemic species of Hawai‘i
- Note that, simply because of the relatively small area involved, many Hawaiian species are considered threatened even when at their normal population levels.
Mammals
- Hawaiian hoary bat (Lasiurus cinereus semotus) - endangered
- Synemporion keana - extinct
- Hawaiian monk seal (Neomonachus schauinslandi) - endangered
Birds
- Hawaiian duck (Anas wyvilliana) - endangered
- Laysan duck (Anas laysanensis) - critically endangered
- Nene (Branta sandvicensis) - vulnerable
- Hawaiian petrel (Pterodroma sandwichensis) - vulnerable
- Newell's shearwater (Puffinus newelli) - endangered
- Hawaiian hawk (Buteo solitarius) - near threatened
- Laysan rail (Porzana palmeri) - extinct
- Hawaiian rail (Porzana sandwichensis) - extinct
- Hawaiian gallinule (Gallinula chloropus sanvicensis)
- Hawaiian coot (Fulica alai) - vulnerable
- Hawaiian stilt (Himantopus himantopus knudseni)
- Hawaiian black noddy (Anous minutus melanogenys)
- Pueo (Asio flammeus sandwichensis) - endangered
- Kaua'i o'o (Moho braccatus) - extinct
- OÊ»ahu Ê»ÅʻŠ(Moho apicalis) - extinct
- MolokaÊ»i Ê»ÅʻŠ(Moho bishopi) - extinct
- Hawai'i Ê»ÅʻŠ(Moho nobilis) - extinct
- Kioea (Chaetoptila angustipluma) - extinct
- KÄmaÊ»o (Myadestes myadestinus) - extinct
- 'Amaui (Myadestes woahensis) - extinct
- Olomaʻo (Myadestes lanaiensis) - critically endangered/extinct
- ‘Ōma’o (Myadestes obscurus) - vulnerable
- Puaiohi (Myadestes palmeri) - critically endangered
- Millerbird (Acrocephalus familiaris) - critically endangered
- Hawaiʻi ʻelepaio (Chasiempis sandwichensis) - vulnerable
- Oʻahu ʻelepaio (Chasiempis ibidis) - endangered
- Kaua'i ʻelepaio (Chasiempis sclateri) - vulnerable
- Hawaiian crow (Corvus hawaiiensis) - extinct in the wild
- Laysan finch (Telespiza cantans) - vulnerable
- Nihoa finch (Telespiza ultima) - critically endangered
- Lesser koa finch (Rhodacanthus flaviceps) - extinct
- Greater koa finch (Rhodacanthus palmeri) - extinct
- Maui parrotbill (Pseudonestor xanthophrys) - critically endangered
- ʻŌʻū (Psittirostra psittacea) - critically endangered/extinct
- Palila (Loxioides bailleui) - critically endangered
- Lana'i hookbill (Dysmorodrepanis munroi) - extinct
- Kona grosbeak (Chlroidops kona) - extinct
- Common ʻamakihi (Hemignathus virens) - least concern
- Oʻahu ʻamakihi (Hemignathus flavus) - vulnerable
- Kauaʻi ʻamakihi (Hemignathus kauaiensis) - vulnerable
- Greater ʻamakihi (Hemignathus sagittirostris) - extinct
- Maui nukupu'u (Hemignathus affinis) - critically endangered/extinct
- Kauaʻi nukupu'u (Hemignathus hanapepe) - critically endangered/extinct
- Oʻahu nukupu'u (Hemignathus lucidus) - extinct
- 'Akiapola'au (Hemignathus munroi) - endangered
- 'Anianiau (Magumma parva) - vulnerable
- Hawai'i 'akialoa (Akialoa obscura) - extinct
- Kauaʻi ʻakialoa (Akialoa stejnegeri) - extinct
- Maui Nui 'akialoa (Akialoa lanaiensis)- extinct
- Oahu 'akialoa (Akialoa ellisiana) - extinct
- 'Akeke'e (Loxops caeruleirostris) - critically endangered
- Hawai'i 'akepa (Loxops coccineus) - endangered
- Maui ʻakepa (Loxops ochraceus) - extinct
- Oʻahu ʻakepa (Loxops wolstenholmei) - extinct
- 'Akikiki (Oreomystis bairdi) - critically endangered
- Hawai'i creeper (Oreomystis mana) - endangered
- Molokai creeper (Paroreomyza flammea) - extinct
- Oʻahu ʻalauahio (Paroreomyza maculata) - critically endangered/extinct
- Maui 'alauahio (Paroreomyza montana) - endangered
- Lana'i 'alauahio (Paroreomyza montana montana) - extinct
- 'Akohekohe (Palmeria dolei) - critically endangered
- Po'ouli (Melamprosops phaeosoma) - critically endangered/extinct
- ʻUla-ʻai-hawane (Ciridops anna) - extinct
- ʻIʻiwi (Drepanis coccinea) - vulnerable
- Hawai'i mamo (Drepanis pacifica) - extinct
- Black mamo (Drepanis funerea) - extinct
- Laysan honeycreeper (Himantione fraithii) - extinct
- 'Apapane (Himantione sanguinea) - least concern
Marine fish
Freshwater fish
- None of Hawaii's native fish are entirely restricted to freshwater (all are either anadromous, or also found in brackish and marine water in their adult stage).
- Oopu nakea (Awaous stamineus)
- Kuhlia xenura (a flagtail species)
- Oopu alamoo (Lentipes concolor) - data deficient
- O'opu naniha (Stenogobius hawaiiensis)
- Sandwich Island sleeper (Eleotris sandwicensis) - data deficient
- Stimpson's goby (Sicyopterus stimpsoni) - near threatened
Invertebrates
Insects
- Hyposmocoma (a genus of moths, such as the snail-eating caterpillar)
- Paralopostega (a genus of moths)
- Mestolobes (a genus of moths)
- Orthomecyna (a genus of moths)
- Scotorythra (a genus of moths)
- Kamehameha butterfly (Vanessa tameamea)
- Green Hawaiian Blue (Udara blackburnii)
- Longhead yellow-faced bee (Hylaeus longiceps)
- Thaumatogryllus (a genus of crickets)
- WÄ"kiu bug (Nysius wekiuicola)
Spiders
- Ariamnes makue (a spider)
- Happy face spider (Theridion grallator)
- Kauaʻi cave wolf spider (Adelocosa anops) - endangered
- Orsonwelles, a genus of 13 species, each endemic to a single island
- Nihoa (a genus of spiders)
Gastropods
- Oahu tree snails (Achatinella) - threatened, several already extinct
- Auriculella (a genus of land snails) - threatened, several already extinct
- Erinna (a genus of freshwater snails) - one vulnerable species, the other possibly extinct
- Gulickia alexandri (a land snail) - critically endangered
- Newcombia (a genus of land snails) - threatened, one already extinct
- Neritina granosa (a freshwater snail) - vulnerable
- Perdicella (a genus of land snails) - threatened, several already extinct
Crustaceans
- Atyoida bisulcata (a freshwater shrimp)
- Halocaridina (a genus of marine and brackish water shrimp)
- Hawaiian river shrimp (Macrobrachium grandimanus)
Cnidarians
- Finger coral ("Porites compressa")
- Thick finger coral ("Porites duerdeni")
- Brigham's coral ("Porites brighami")
- Moloka‘i cauliflower coral ("Pocillopora molokensis")
- Irregular rice coral ("Montipora dilatata")
- Blue rice coral ("Montipora flabellata")
- Sandpaper rice coral ("Montipora patula")
- Verril's lump coral ("Psammocora verrilli")
- Serpentine cup coral ("Eguchipsammia serpentina")
- Grand black coral ("Antipathes grandis")
- Bicolor gorgonian ("Acabaria bicolor")
- Small knob leather coral ("Sinularia molokaiensis")
Plants
- Yellow hibiscus (Hibiscus brackenridgei) - endangered
- Loulu â€" (Pritchardia fan palms)
- Alula (Brighamia insignis) - critically endangered
- Pua ʻala (Brighamia rockii) - critically endangered
- Koa (Acacia koa)
- 'ÅŒhi'a lehua (Metrosideros polymorpha)
- Lehua mamo (Metrosideros macropus)
- Lehua papa (Metrosideros rugosa)
- Lapalapa (Cheirodendron platyphyllum)
- ʻŌlapa (Cheirodendron trigynum)
- MÄmane (Sophora chrysophylla)
- Lobelia niihauensis - endangered
- Lobelia oahuensis - critically endangered
- Clermontia pyrularia - critically endangered
- Cyanea platyphylla - critically endangered
- Cyanea superba - extinct in the wild
- Cyanea truncata - extinct in the wild
- Kanawao (Broussaisia arguta)
- ʻĀkala (Rubus hawaiensis)
- ʻĀkalakala (Rubus macraei)
- Greensword (Argyroxiphium grayanum)
- Hawaii silversword (Argyroxiphium sandwicense)
- ʻEke silversword (Argyroxiphium caliginis)
- Mauna Loa silversword (Argyroxiphium kauense)
- Argyroxiphium virescens
- Hawaiian Iliau (Wilkesia gymnoxiphium)
- Dwarf Iliau (Wilkesia hobdyi)
- Tree dubautia (Dubautia arborea)
- Keaau Valley dubautia (Dubautia herbstobatae)
- Bog dubautia (Dubautia imbricata)
- Kalalau rim dubautia (Dubautia kenwoodii)
- Small-headed dubautia (Dubautia microcephala)
- Wahiawa bog dubautia (Dubautia pauciflorula)
- Plantainleaf dubautia (Dubautia plantaginea)
- Net-veined dubautia (Dubautia reticulata)
- Wahiawa dubautia (Dubautia syndetica)
- Waiʻaleʻale dubautia (Dubautia waialealae)
- Koholapehu (Dubautia latifolia)
- Dubautia kalalauensis
See also
- Canoe plants
- Endemic birds of Hawaii
- Environment of Hawaii
- Hawaiian lobelioids
- List of extinct animals of the Hawaiian Islands
- List of Hawaii birds
References
Further reading
- Sakai A. K.; Wagner W.L.; Mehrhoff L. A. (2002). "Patterns of Endangerment in the Hawaiian Flora". Systematic Biology. Society of Systematic Biologists. 51 (2): 276â€"302. doi:10.1080/10635150252899770. PMID 12028733.Â
External links
- Flora of the Hawaiian Islands from the Smithsonian Institution