When I learned that the trail maintenance crew of the Hawaiian Trail and Mountain Club (HTMC) found several native snails and happy face spiders on the top of Mount Kaala, I had to climb to the summit to see them with my very own eyes.
Mount Kaala is the highest mountain on O’ahu which stands 4,025 feet above sea level and is often shrouded in a foggy mist. Surrounded by steep cliffs, the flat-topped summit is home to scores of native plants and animals found only in Hawaii.
The chilly early morning air kept me cool as I made my way up the Waianae-Kaala Trail. The trail starts at about 600 feet elevation and gains 3,400 feet to reach the summit over a distance of 4 miles (for a round trip of 8 miles).
The steep climb up the narrow ridge to the summit of Kaala offers excellent cardiovascular exercise. As I climbed up and over the large boulders that block the trail, clouds descended and created ideal conditions for kahuli or land snails who prefer cool and moist conditions.
During my climb up the steep trail, I looked for kahuli on each olomea tree I encountered. I am sad to report that I was only able to find two endemic Oahu Tree Snails (Achatinella mustelina) — a young adult just over half an inch across and a cute little baby a little more than an eighth of an inch across. Just 3 years ago they were not overly difficult to find, but now these endangered creatures can only be found with considerable effort.
The steep slopes of Mount Kaala are also home to white kahuli (Auricullela ambusta) which live on ohia and other trees. These endemic snails are are about a quarter inch long and are found in the wet and mesic forests of Oahu. While they are not endangered they are not commonly seen.
When I reached the top of Kaala, clouds blew-in and blocked the panoramic view of the Waianae Coast. At 4,025 feet, the summit plateau harbors one of the most extensive cloud forests on the island. Alani kuahiwi (Melicope clusiifolia), which is endemic to Hawaii, thrives at the summit of Mount Kaala and is typical of trees that live in cloud forests — they are shorter and more heavily branched than trees at lower elevations.
Fine mists repeatedly rolled-in, enveloped the landscape, and dissipated multiple times during the day. Trees in cloud forests are often covered with mosses and ferns. Much of the precipitation in cloud forests is received in the form of fog drip — water from passing clouds condense on the mosses and ferns covering the trees and then slowly drip to the ground below. As a result, the ground is soaked, water-logged, and boggy.
Endemic lapalapa trees (Cheirodendron platyphyllum) and hapuu tree ferns (Cibotium chamissoi) thrive in the wet water-logged conditions at the summit of Kaala.
The boardwalk at the summit prevents the ground from being trampled into a muddy morass. As I made my way through the mist I saw a number of koli’i (trematolobelia macrostachys) along the boardwalk. Kolii is endemic to Hawaii and while it is not endangered it can only be found at a handful of locations on Oahu.
When I examined the leaves of plants along the board walk I saw several dozen succinea snails nearly half-an-inch long. These kahuli (Succinea catinella rotundata) are endemic to Hawaii and are fairly common in wet areas of the island. Also known as “snot in a hat”, succinea snails have extremely thin translucent shells that are too small for the snail to completely retract inside — hence their endearing nickname.
Mount Kaala is also home to philonesia snails about a quarter-inch long whose shells are round and flat in shape. These kahuli (philonesia snails) are also endemic to Hawaii and are fairly common in wet areas of the Waianae mountains.
Kanawao (also known as puahanui), the endemic hydrangea (Broussaisia arguta), were in bloom throughout the bog. One of the more interesting features of kanawao is that it produces two types of plants — male plants which have flowers that only have stamens (the male part of the flower), and female plants which have flowers that only have pistils (the female part of the flower).
The flowers of the male plant only have stamens which open-up to produce pollen. Non-native hover flies pick-up pollen from male flowers and transport them to female flowers.
The flowers of the female plant only have reddish-pink pistils which must be pollenated in order for fruit to develop. The strategy of having separate male and female plants and flowers are a means for the plant to ensure its flowers are not self-pollenated.
While making my way across the boardwalk, I was thrilled to find a tiny happy face spider whose body was less than a quarter-inch long of the underside of a leaf. The legs of the spider were extremely long and thin, and extended for nearly an inch. Except for the happy face pattern on its abdomen, the rest of the spider was nearly translucent.
Known as “nananana makaki’i” in Hawaiian, happy face spiders (Theridion grallator) are endemic to Hawaii. These spiders are highly polymorphous with each island evolving its own forms with unique markings on its abdomen — many spider do not have a “happy face” pattern on their abdomens at all.
Time passed quickly at the summit and soon it was time for me to leave. As I made my way back down through the mist, I recalled the ‘olelo no’eau (Hawaiian proverb) “Ka ua kolowao o Ka‘ala” which means “the rains of Ka’ala are accompanied by mists that creep among the trees”, and reflected on how lucky I was to see the amazing plants and animals that live in the mists of Mount Ka’ala.
Cloud Forest, Wikipedia
Happy Face Spiders, Interview with an Expert, U-Haul
The happy face spiders, Understanding Evolution
‘Olelo No‘eau, Hawaiian Proverbs & Poetical Sayings. Pukui, M.K. 1983, Bishop Museum Press. Honolulu, HI.
Personal communication with Daniel Chung, University of Hawaii and Bishop Museum