29 Jun New Deep Water Palau Shell
A new deep-water slit shell, a type of gastropod mollusc (snail), has been described from Palau as a new species, Bayerotrochus belauensis . While specimens had been collected before, it was mistakenly identified as a species of slit shell that occurs in Japan. The Coral Reef Research Foundation (CRRF) on Malakal collected three specimens in 2001 using the Deepworker submersible at depths of 710-775 ft. By sequencing the DNA and further morphological studies, it was determined that the Palau specimens represented an undescribed, new species. This new species, presently known only from Palau, was recently described in the journal ‘The Nautilus’ by experts in the field. The snails were found on both rock and sediment substrates, where water temperatures are a cool 50-55oF (10-13oC). This iconic species lives in the same habitat where the Nautilus (kedarm) and deep water snapper (sebus) occur on the outer reefs of Palau. A specimen of this new species can be seen at the Etpison Museum in Palau.
Slit shells are loosely related to the more familiar Trochus shells (semum), with a similar conical shape and size, and mother-of-pearl inside. The slit shells are more fragile with thinner shell walls and are only found in deep water. They are distinct from Trochus in having a narrow open slit in the leading edge of the last whirl of the shell which is used for excretion of waste products. They are generally large and colorful, and seldom caught as they are restricted to deep water. While the attractive shells were sometimes caught in traps during deepwater fishing in Japan in the 1700’s, they were considered so rare and special that any recovered were required to be given as gifts for the Emperor. Hence the Japanese species have been known as the “Emperor’s Slit Shell” (okinaebisugai).
The scientific paper naming the Palau Slit Shell is available here.
Underwater photos of Palau’s new slit shell, Bayerotrochus belauensis, taken at 710-775 ft. in 2001 with an external camera on the Deepworker submersible (right). A & B (left) show the shell covered in a new species of zooanthid (anemone-like creature) while the specimen in C (center) had a bare shell and is seen feeding on a deep-water sea pen.