This is Achatinella apexfulva.

It is the type species of the genus Achatinella, or, the Hawaiʻi tree snails, or, the kāhuli.

In traditional beliefs, these small, arboreal snails are one of the few things in nature capable of creating sound, along with wind, rain, thunder, earthquakes, and birds. Many believe kāhuli can be heard singing as they glide up and down trees - often described as a “chirping” or “whistling” sound. Some say it is the sound of the wind gently caressing their shells, as they travel slowly across a leaf, swaying gently from side to side.

The sound has been referred to as “the voice of the forest”. Astronomer Henry Glanville Barnacle, who travelled to the archipelago in 1874, wrote: “it is the grandest but wildest music, as if from hundreds of Aeolian harps.”

Kāhuli and their song feature heavily in the traditional tales of the islands, signalling romance, affirmation, and peace. Their shells, strung together to make wreaths, can be worn by dancers to deepen their affinity with a chant or a story.

Kāhuli were once so common on the islands, that if you shook a tree it would rain snails, with shells of a multitude of different colours, sizes and patterns. Tourists delighted in collecting them, sometimes thousands at a time.

Despite its continued cultural significance, most of the islands’ people have never seen - or heard - a kāhuli. Of the 41 documented species, just 11 endure, and all of them are endangered. Some of them are so rare that just a few specimens remain, on one tree deep in the forest.
The last individual of A. apexfulva, affectionately named George, died in 2019.

George was born in a mobile laboratory in 2005 on the island of Oʻahu. Their parents were two of 10 snails collected by scientists in 1997 in a desperate attempt to save the species from the predatory rosy wolfsnail (Euglandina rosea). This cannibalistic snail was introduced to the islands in 1955 to counter the threat of another introduced mollusc, the giant African land snail (Achatina fulica), but it had an immediate and devastating impact on the kāhuli, which has a very slow reproductive rate.

All kāhuli are both male and female simultaneously - simplifying breeding somewhat - but unlike most snails, they give birth to just one live young at a time, a few times a year. In its 10-year lifespan, one kāhuli can only produce 30 offspring.

In the lab on Oʻahu, a few young were born, but generally the captive individuals did not thrive. One by one, the adults and juveniles died. George, however, managed to survive, and lived more than a decade as an “endling”, or, the last member of a species. They died sometime in the morning of New Years’ Day, 2019.

Mai hōʻeuʻeu mai ʻoe
I ka wai ua lana mālie
E kakali mālie ʻoe
A laʻi pono ka makani

ʻAuhea wale ana ʻoe Uhiwai o Kaʻala
I pili me ka Malua
Ka makani o ka ʻāina

Hoʻokahi au mea uluhua
Ka makani anu la he Kiu
Houhou ana i ka ili Konikoni i ka iwi hilo

ʻAʻole i piliwi ia
Leo hone o ke kahuli Hone ana i ka pō la`i
I ke kulukulu aumoe

You must not be anxious to rush
Into the water that appears serene You must wait patiently
Until the wind calms down

Pay attention
Fog of Kaʻala
Associated with the Malua wind
The wind of the land

The one thing I worry about
Is the strong, chilly, northwesterly wind That pierces the skin
And causes my bones to shiver

Unbelievable
The sweet voice of the kāhuli
Singing in the still night
In the late night

It is thought the common ancestor of all kāhuli would have arrived on the archipelago on a mat of debris which was sent out to sea after a large storm or tsunami, possibly from a land mass many thousands of kilometers away.

They then evolved through non-adaptive radiation - speciating not as a response to predators or specific conditions, but rather though their general immobility. A species might only inhabit one particular hilltop or small patch of forest, even in the absence of a geographic or climatic barrier.

One kāhuli usually spends its entire lifespan on just a single tree, but they do not eat the trees. Rather, they graze on the thin, transparent film of algae and fungus on the bark and leaves. They scrape it off with their tongue, creating faint, winding trails on the surface, but leaving the tree completely unharmed.

There are conservation efforts to save the remaining species of this graceful snail. Electrified fences have been constructed around many of the known vulnerable populations, which are effective in keeping out predators, but need constant monitoring.

Outside these enclosures, amongst the hundreds of new, invasive plant and animal species of the islands, the kāhuli and its gentle song have all but disappeared.