The reef is full of interesting creatures and fascinating adaptations and survival techniques used by reef inhabitants to prevent becoming food to predatory fish. Often this survival evolution results in some interesting partnerships between marine creatures. One of the more curious relationships that most divers would have come across, is that between the marine goby fish and the shrimp.

The Pistol Shrimp or Snapping Shrimps of the Alpheus shrimp, family are great diggers, and constantly create and maintain burrows in the sea beds sand using its large claws. However the shrimp have really poor eye-sight and being almost blind, cannot spot their predators until it’s too late. The Goby fish  (Gobies in the genus  Amblyeleotris, Cryptocentrus, Ctenogobiops, Istigobius, and Stonogobiops) on the other hand are small vigilant fish that form a symbiotic relationship with the shrimp and act as the shrimp’s watchman against predators, in exchange for shelter in the shrimp’s burrow.

The goby will usually sit at the entrance of the burrow maintaining a constant vigil against potential predators, while the shrimp bulldozes away clearing gravel from the burrow. Whenever the shrimp needs to dump gravel outside the burrow, it is usually exposed to potential predators. However with the Goby keeping lookout, the shrimp places one tentacle on the Goby while exposed, so if the Goby darts inside the burrow, the Shrimp instantly is alerted of the presence of a predator and it too darts back inside the safety of its burrow. The partnering between these two creatures is only that of a watchman and housekeeper. Gobies eat micro-fauna and sometimes tiny fish they find near the bottom, the shrimps feed on what they find in their burrowing and hence do not compete for food.

So how do the Gobies and Shrimp find each other in the first place? Shrimp-goby researchers have been trying to figure out this one for a long time, and have conducted numerous experiments  to determine whether the Gobies find the shrimp, or vice versa, and also to determine whether they locate each other optically or are attracted chemically. There has been no definitive answer as to who spots who in this symbiotic relationship and it is still one of nature’s mysteries.

So the next time you spot a goby while scuba diving, perched vigilantly near a burrow, look closely and you will more often than not, spot the housekeeper shrimp hard at work bulldozing clawful after  clawful of sand. Spend some time watching this interesting relationship and I can tell you , you will not be disappointed.

Photos from flickr by: Nick Hobgood, PacificKlaus. Boogies with Fish

Snapping Shrimp better known as Pistol shrimp are tiny finger sized creatures that are seldom seen but almost always heard! Most popularly known with divers for their ceaseless cacophony that colonies of these shrimps produce; these shrimp emit  loud crackling sound almost as if a hundred people are cracking their knuckles at once.

Upon closer inspection of the snapping shrimp, it has two claws one of which is an oversized claw that resembles a boxing glove almost as big as its body that it uses to stun its prey by snapping the claw shut quickly. The action produces a loud cracking sound which produces a sort of sonic blast, the shockwave of which is sufficient to stun a passing crab.

Recent research into the Snapping shrimp has generated much interest after discovering that this tiny creature’s claw snapping motion actually shoots out a jet of water at up to 60 miles an hour which generates a low pressure bubble that bursts with a loud snap. The snap of this bubble can produce something known as sonoluminescence which is caused when the collapsing bubble reaches temperatures of over 4700 degrees Celsius or 5000K which is almost as hot as the surface of the sun which is 5778 Kelvin! The resulting snap also produces light which is of a lesser intensity and not visible to the naked eye.

Many who have tried to keep Pistol Shrimp in aquariums at home will testify that they are simply impossible to rear. The sonic blast of these tiny creatures has cracked the aquarium glass so many times, that most hobbyists simply give up.

Another fascinating fact of these amazing creatures is that Naval Submarines have been known to hide amongst beds of Pistol shrimp to hide from sonar detection. Apparently the noise they create is so much that other submarines find it impossible to pickup other noises using sonar.

Pistol Shrimp are native to the tropical waters of the Indo-Pacific and the western pacific regions around  Baja California mostly inhabiting caves, bay or lagoons present on rubble at the bottom.

Another unique feature is the Pistol Shrimp shares a symbiotic association with the goby. The goby has a good eye-sight and thus, warns the shrimp of any approaching predator in the exchange of food that the shrimp provides to the goby and the burrow that the Shrimp digs for both, itself and the goby, to live in.

So the next time you hear the loud snap, crackling and pop while diving, take some time out to investigate, and you will be quite amazed at discovering its source.

photos by: divemasterking2000, budak