Thought to be extinct until it was discovered again in 2007
The Borneo shark (Carcharhinus borneensis) is a species of requiem shark, and part of the family Carcharhinidae. Extremely rare, it is known only from inshore waters around Mukah in northwestern Borneo. It is small and grey and has pores around its mouth.
Family: Carcharhinidae – Requiem sharks
Common Name– Ground Sharks
Common Name– Requiem Sharks
Status: IUCN Red List ENDANGERED
Average Size and Length: The Borneo shark can reach 2.1 feet in length.
Teeth and Jaw: The corners of the Borneo sharks mouth have short, indistinct furrows, and immediately above are a series of enlarged pores, completely unique to the Borneo shark. There are 25–26 upper and 23–25 lower tooth rows. The upper teeth have a single, narrow, oblique cusp with strongly serrated edges, and large cusp-lets on the trailing side. The lower teeth are similar, but are more-slender and much more finely serrated.
Head: The Borneo sharks’ snout is long and pointed. It has slit-like nostrils with flaps of skin. The eyes are large and circular, and have nictitating membranes.
Denticles: The dermal denticles of the Borneo shark are small and overlapping, each with three horizontal ridges leading to marginal teeth.
Demographic, Distribution, Habitat, Environment and Range: The Borneo shark inhabits the inshore, coastal waters of in Sarawak. Most recently, just in Mukah. Only 5 specimens have ever been collected. One was found in Zhoushan Island, one from Java, another from Borongan.
Diet: What little is known about the Borneo shark, they are thought to mostly east bony fish.
Aesthetic Identification: The Borneo shark is a small shark, and thin looking. It has 5 pairs of short gill-slits. The Borneo shark is dark grey on top, and further darkening towards the fin tips. Occasionally, the Borneo shark may have small white blotches, which is thought may be a product of handling. The Borneo shark is counter-shaded white under its belly.
The pectoral fins of the Borneo shark are short, pointed, and falcate, while the pelvic fins are small and triangular with a nearly straight trailing margin. The first dorsal fin is large and triangular, with a blunt apex sloping down to a sinuous trailing margin; its origin lies over the free rear tips of the pectoral fins. The second dorsal fin is small and low, and originates over the middle of the anal fin base. There is no ridge between the dorsal fins.
Biology and Reproduction: The Borneo shark is viviparous. From what we know, the litter size is 6. The pups are born at 9.4–11.0 inches long. From the available specimens, the length at sexual maturity can be inferred to be under 22–23 inches in males and under 24–26 inches in females.
Behavioral Traits, Sensing and Intelligence: Very little is known about the behavioral traits of the Borneo shark.
It is important to note the unique, enlarged pores, and perhaps these pores are unique to its sensing.
Borneo Shark Future and Conservation: The Borneo shark is very rare and endangered. It was thought to be extinct until it was discovered again in 2007. The Borneo shark is at risk of being caught up by line gear in commercial fishing. This shark needs our help and protection. We need to raise more money for conservation and for research of the Borneo shark.
Borneo Shark Recorded Attacks on Humans: No threat to humans.