Tag Archives: diving around the gili islands

Facts about Unicorn Tangs

Interesting Facts About Unicorn Tangs

Unicorn tangs or Naso unicornis are members of the family Acanthuridae commonly refer to as surgeonfish. There are 80 species in 6 different genera in this family. All have one distinguishing characteristic. They have sharp blades at the base of their tails (caudal peduncle) on both sides of their bodies that are used in self-defense. Seventeen of the 80 species are unicornfish. Here we will be elaborating on the unicorn tang. They are endemic to the Indo-Pacific from Indonesia and Christmas Island westward to the Andaman Sea, south to the eastern coast of Africa and east to the Hawaiian Islands. When you are diving around the Gili Islands you will find the everywhere.

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Facts about Porcelain Crabs

Porcelain crab
Neopetrolisthes maculatus

These delicately spotted crabs live in a symbiotic relationship with anemones. They keep the anemone clean while benefiting from its protection. Porcelain crabs have modified mouthparts which open out like fans into the oncoming current in order to trap tiny particles of plankton

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Life span

They live for around 2-3 years.

Statistics

They are less than 24mm in width.

Distribution

They are found in the Indo-Pacific. You see them when you are diving around the Gili Islands Indonesia.

Habitat

They are also known as anemone crabs, due to their close association with anemones. Porcelain crabs may be found singly or in pairs, hidden between the stinging tentacles, or near the mouth, of anemones. They are found in reef habitats, to depths of around 10m.

Diet

They are mainly plankton feeders, sieving tiny particles from the water column using their fan-like mouthparts. They also eat mucus from the anemone.

Behaviour

Porcelain crabs are relatively aggressive, using their large claws to deter invaders, including anemone fish. Although both use an anemone host, porcelain crabs and anemone fish are not commonly found together, the crab usually losing out to the tougher fish. Like anemone fish, porcelain crabs are immune to the anemone’s stinging tentacles. It is a mutualistic relationship, since both parties benefit from the arrangement: the crab gaining safety and shelter, in return for cleaning.

Reproduction

Porcelain crabs are often found in heterosexual pairs. They have internal fertilization, the male passing sperm to the female in the form of a tiny packet called a spermatophore. The eggs are carried by the female in a brood flap, on the abdomen. A single female may carry nearly 1,600 eggs at a time. The larvae are planktonic for several weeks before settling.

Conservation status

Porcelain crabs are not of the IUCN Red List, but suffer from habitat loss if reefs are damaged or polluted.

Facts about Trumpetfish

TRUMPETFISH (Aulostomus chinensis)

Also known as Trumpet, Atlantic Trumpetfish, Caribbean Trumpetfish, Trumpeter and Painted Flutemouth. You can find them everywhere around the Gili Islands when you are snorkeling or divinvg.

The Trumpetfish can be recognised by its long body, tubular snout with minute teeth, its chin barbel and the series of short dorsal spines.Their bodies are inflexible, supported by interwoven struts of bone. The colouration of this species is variable. It is often brown or green with pale stripes and bars, and white spots posteriorly. A yellow colour variety is common in some areas. Individual fish have the ability to change their colours very quickly. Trumpetfish have the capability to rapidly expand their jaws into a circular gaping hole almost the diameter of their body when feeding.

The trumpetfish is the true master-hunter on the coral reef. Yes, this fish looks rather benign and yes it is a relative of the passive sea horses, but it is truly a fish-killing machine! The trumpetfish employ a variety of strategies to capture their fish neighbors. One of the most spectacular is referred to by fish behaviorists as “hunting by riding” (a.k.a. shadow stalking). This is where the trumpetfish uses another fish as a blind to sneak-up on its unsuspecting quarry. The hunter-extraordinaire will lie along the back of the larger fish as the latter swims over the reef. The species that the trumpetfish uses as a blind are usually large herbivores (e.g., parrotfishes) or omnivores (e.g., angelfishes). Because these species don’t cause small fish to flee (because they do not feed on them), the trumpetfish can hide behind them to get close. Once the distance between predator and its prey reaches a critical point, the trumpetfish will dart out from its living blind like an amphibious arrow! While it may look like the trumpetfish has a relatively small mouth, the floor of the narrow snout is very expandable, which enables it to distend so larger prey can pass into the stomach. If you see a trumpetfish while diving, stay back and watch it for a while. There is a good chance you will see it engage in this fascinating hunting behavior.