When diving over sand area’s of a dive site there are so many interesting critters that are often not seen or ignored by divers, one of these is the symbiotic pairing of the goby and shrimp.

Almost all of our dive sites by there nature have sandy bottoms and instead of passing quickly over them it is good to swim slowly and enjoy watching the behavior of these interesting room mates.
The sandy bottom of the reef is full of interesting creatures and fascinating methods have been devised for survival techniques used by reef inhabitants to prevent becoming food to predatory fish. Often this results in some interesting partnerships between marine creatures. One of the more curious relationships that most divers could have come across is that between the goby fish and the shrimp.
The little goby that firmly stands his ground outside his burrow belongs to a very special group of gobies called “shrimp gobies”. There are 70 or so brightly coloured shrimp gobies recorded worldwide in tropical waters and the western Indo Pacific is home to most of them. Their uniqueness is that they live in partnership with “pistol shrimps”. Pistol shrimps are so named for the loud snapping sound and the jet of water that comes from the rapid closing of a modified claw.

The gobies spend their day near entrance ways keeping their eyes peeled for predators, such as jacks and lizardfish, while the hard-working shrimp bulldoze sand into the open from the burrow below.
The front entrance of the burrow is often reinforced with bits of shell and coral put in place by the shrimp.

The goby will usually sit at the entrance of the burrow maintaining a constant vigil against potential predators, while the shrimp is 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 is instantly alerted of the presence of a predator and it too darts back inside the safety of its burrow. Often pairs of gobies or pistol shrimps will inhabit the same burrow.

They work between sunrise and sunset, resting with the gobies, inside the burrow at night. And like most homes, burrow construction varies according to its inhabitants. Scientists have even found that the sizes and shapes of burrows depend on the type of sediment available and to some degree on the species of shrimp. So the goby gets a professionally constructed and safe house away from predators, and somewhere to lay its eggs.
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 they do not compete for food.

The special relationship that exists between these two species is called symbiosis. Symbiosis literally means “living together” and can take more than one form but it is always between individuals of different species. It can mean, for example, that only one of the species benefits with no effect on the other, or that one species of the pair benefits but the other is harmed in the process. In the shrimp-goby case both species gain equal benefit and they significantly increase their chances of survival in a hostile world. This particular type of symbiosis is called “mutualism”. Their relationship is one that has developed through a mutual need and benefit to both species.

These animals are dependent on each other. Remove the fish, and the shrimp stops burrowing; the shrimp forage while burrowing, so without a fish, they grow more slowly. The shrimp need their guard goby, and the guard goby needs its shrimp: deny the goby shelter in a burrow, and it will promptly be killed by predators (someone did the experiment). The shrimp keep the goby clean, too: they groom it.

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 but it appears that the short sighted shrimp uses chemical senses, and the goby uses it’s much better developed visual sense for finding each other at a very young stage of their life.

Find out more about interactions and partnerships by taking the underwater Naturalist  specialty course with Scuba Cat and see the goby and shrimps at many of our dive sites both by daytrip and liveaboard.

The lionfish is a common site in the Andaman and seen on all of the dive sites we go to, both by daytrips and liveaboards.
Nobody knows for sure how they got their name, and they are also known as turkey or dragon fish in some area’s. One thought is when they spread out their pectoral fins it sort of looks like a lion’s mane, and they are ferocious predators

They are beautiful and fascinating fish but due to their colouring, as is common in nature, most times bright and beautiful means dangerous. Its bright colours advertise its poisonous tentacles. The venom of the lionfish, delivered by up to 18 needle-like dorsal fins and is purely defensive. A sting from a lionfish is extremely painful to humans and can cause nausea and breathing difficulties, but is rarely fatal.
The scientific name for the lionfish is Pterois, and there are fifteen different species in the Pterois Genus of fish.

The largest of the lionfish species can grow to about 40cm in length, but the average is closer to 30cm, with the smallest around 6cm, and they weigh somewhere around 500 to 900g. Their lifespan in the wild can be around 15 years.

They are mainly active during the day and at night the Lionfish find crevices among rocks that they rest in, this is so they are not out of the open where they would be at risk of predators consuming them.

It relies on camouflage and fast reflexes to capture their prey which is mainly fish and shrimp.. Adult lionfish use their distinct pectoral fins to attract the prey. As soon as the prey comes within their reach, they swallow it in a single motion. Though not quite unique, this method of hunting is highly successful in regions where the lionfish is a non-native species as the native population of the area is not used to such traps. They are able to move around very quickly in the water. They are very good at using those long pectoral fins to herd fish and other prey into a confined area, trapping it making it simple for them to get their food. The lionfish’s stomach can expand to 30 times its normal size so they can really fill up, this is why it is such an invader in the Caribean.

They are solitary and they will become very aggressive if they feel that their home territory is at risk. The males tend to be more aggressive overall than the females. While adult lionfish are solitary creatures, juveniles are known to live together in groups. Over the course of time, they become highly territorial and don’t even hesitate to take on the other members of their group to capture and/or defend their territory.

The native habitat of lionfish spans the rocky crevices and reefs of the Indo-Pacific waters, but they can be found in the eastern coast of America. It is not clear how they have found their way there but it is thought that some specimens who were released by certain aquariums, and have begun to thrive in these warm waters without any natural predators. There is one documented case of lionfish escaping from an aquarium located in a house damaged by Hurricane Andrew – the fish were seen swimming nearby after the storm. The “on purpose” introductions are assumed to occur from hobbyists who dumped them into canals (not knowing any better) when the fish either got too large for their aquariums or became unwanted. Genetic evidence from recent scientific results suggests multiple introductions.

Learn more about marine life in the area with our AWARE Fish ID, Naturalist or Advanced open water courses.

Family name: Antennariidae
Order name: Lophiiformes
Common name: Frogfish or Anglerfish
Scientific name: Antennariidae
Frogfish are very misunderstood and very little is known about this unique underwater lie-in-wait predator. They live generally on the ocean floor around coral or rock reefs throughout tropical and subtropical waters. Most species live in shallow water although some species are deep dwelling. Recreational divers in Asia are most likely to spot certain species including giant, clown and painted frogfish.

Around the Andaman we have seen frogfish in the Similans, Richelieu Rock, Koh Tachai, Koh Doc Mai, Phi Phi, Racha Yai and Noi.

Frogfish, are named because of their squat resemblance to the common amphibians, they range in size from around 5cm to the giant frogfish’s 40cm. The resemblance to frogs is that their fins are more like legs, which they use to walk slowly over the sea bed and on top of sponges and corals to lie in wait for their prey.
Colour is often not much help in identifying different frogfish since they can change this to allow themselves to camouflage and blend in with the environment they are in. Depending on the species, this change might take seconds or weeks. Some frog fish’s skin is also covered by bumps, flaps, hairs and tassles which further allow for mimicking the nearby seabed, corals, sponges or weeds. This also explains how divers can often cruise straight past, not noticing their presence.

There are not many other fish that you could mistake for a frogfish but it can be exceptionally difficult to distinguish between the sexes or species. Unless you get out your scalpel, there is no way to tell male from female. Since colouration is not a method of identification for all but the most rare species, you should be looking out for species-specific features such as what form the lure takes (maybe it is mimicking a worm or fish), the number of eye spots and the number of spines.
Frogfish move very slowly but they have the fastest strike speed of any other animal on earth. They move by gulping water with their massive mouth, then forcing the water through the gills, this allows them to move about the reef or bottom.

As the frogfish is scaleless and unprotected camouflage is an important defense against predators. Some can also inflate themselves, like pufferfish, by sucking in water in a threat display. In aquariums and in nature, frogfish have been know to when moved from their hiding spots and are clearly visible, to be attacked by clownfish, damselfish, and wrasse, and even to be killed.
It is the feeding approach of anglerfish that makes it such interesting creatures. They are perfectly camouflaged and lie in wait for any prey. The lure may be used to attract prey in a variety of different ways, depending on the species.

They can also use a chemical attractant so sometimes they just lie in wait for some unfortunate creature to venture too close. When the prey is within grasp the attack takes place. The frogfish expands its oral cavity engulfing the prey with a reflex that instantly sucks it in by creating suction pressure inside the mouth. Taking no more than around 6 milliseconds.

Frogfish have also been seen stalking their prey by sneaking towards their target along the sea bed.

They eat mostly small fish, shrimps and crabs but their prey sometimes being up to twice their own body size. As they are toothless the frogfish swallows its prey whole, allowing digestive enzymes to do the rest. The prey can often be seen twitching and writhing against the walls of the its stomach until they no longer are alive. Frogfish have also been observed to eat lionfish; the poison appears to have no effect on them.  In addition to expanding their mouths, frogfish can also expand their stomachs to swallow animals up to twice their size.

What eats anglerfish? the main answer is another frogfish, they are known for being cannibalistic. However considering that they are designed more to catch fish swimming in the water column, this is a rather rare phenomenon. Moray eels have also been witnessed eating frogfish, but again, this is an uncommon sight.

Learn more interesting facts about the local marine life to Phuket by joining us on a Naturalist or Fish ID specialty course.

Peacock Mantis Shrimps (Odontodactylus scyllarus)

They are found in the indo Pacific region and we have many of these on all of the dive sites we visit, but you do have to look closely for them.
Although called shrimp they are not actually true shrimp, but a separate family of crustaceans called Stomatopods.

They are mostly found at the base of reefs where they build their burrows, the excavate a u shape tunnel by collecting nearby rubble or other substrate to go over and around suitable sites of rock crevices or corals.

They are very colorful and flamboyant when you find them, with red, green and blue warning coloration.

They feed on various fish and invertebrates and are fast, efficient hunters, though they often wait for their prey to walk by and pounce on them. The peacock is a ‘smashers’ type of mantis shrimp it has two club-like appendages to exo skeleton animals such as crabs, clams and snails. With just one hit the ‘club’ produces a force almost as fast as a 22-caliber bullet, 10m per sec, and this has been know to break aquarium glass. This is so fast it can actually vaporize the water at the point of impact!

In addition to the smashing clubs they also have a shorter body compared to the longer, very flexible tail, this lets them turn quickly and easily in tight spaces and burrows. The tail and the specialized swimming appendages on its underside provide a surprisingly fast swim when on the hunt, or when they get scared.

The eyes are stalk like which allows them to accurately see their prey from the protection of the crevices they live in, the eyes are complex with at least 8 types of different colour sensors, which include ultraviolet and polarized light. They can see 10 times more colours than humans.

From the mantis shrimps that have been kept in captivity, we have learned that they are the only invertebrates that can actually recognize individuals, they do this by body odor!!
They can be aggressive with others of there own species and get into fights using the flexible tails, they sometimes can fight to the death, but often decide who is victorious before either gets seriously hurt.

Some of the shrimps can mate for life, which can be up to 20 years, whilst others prefer a one-night stand. They usually court then come together. The female can hold fertilized eggs under the tail or in the forearms, or they can be laid in burrows and are watched over until they hatch into Larvae. These larvae are also keen predators often preying on other larvae during the 3 months it takes to hatch.

To see these fascinating shrimps you can join us on our daytrips or liveaboards where they are often seen at the divesites, ask our staff about them and other interesting creatures we have in the waters of Thailand.

Learn more about the marine life in our area by taking the Naturalist specialty course with us.

Banded Sea Snakes are found in the tropical waters of the Indo-Pacific region.  The Latin name is Laticauda Colubrina and belongs to the Laticaudinae family. Snakes within this family are able to survive on land and in water.

"Banded sea Snake"

The snakes frequent shallow water as they must surface to breath air. This curious snake with it’s placid nature is recognised by it’s black bands that run the full length of the light blue body. On the underside there may be cream or yellow colouration. The amount of bands vary between 20 and 65.  The tail is laterally compressed, thus acting as an oar helping to propel themselves through water.  The snake has valvular nostrils with valve like flaps, which close upon submersion. Snakes do not have gills, but they have a left lung that runs almost the entire length of the body. The eyes are protected not by eye lids, but modified scales. The face is highlighted with yellow on the snout, upper lips and bar above the eyes.

"Close up of Banded Sea Snake"

Typically, the female is larger than the male. Lengths may vary from 75cm to 200cm. The maximum recorded length of a Banded Sea Snake is 360cm!! This reptile has ventral plates which helps it to move on land. They are oviparous, which means that they return to the land to lay their eggs.  The males of the species have two penises, but only one is used when mating. This is known as hemipenes. Once the eggs hatch the young make their way to the sea.  Sea snakes move in the water relatively slowly, which means that they are unable to chase fish. The juevenile snakes rely on sand smelts and sand perches for food. As they develop they switch their diet to damsel fish and surgeon fish in addition to crabs, cuttlefish, eels, fish eggs and squid.

"Banded Sea Snake at the Surface"

Banded Sea Snakes are often seen hunting in crevices. The fixed front fangs are very small and are designed to immobilise prey. This highly venomous marine reptile releases a neurotoxin, which affects the nervous system.  The snakes produce 10-15mg of venom. A fatal dose is as low as 1-5mg, that is ten times more lethal than a rattle snake and black mamba. It is possible for a decapitated snake to produce a life threatening bite, so fishermen should be aware!!!!

This is an inquisitive creature that can be mistaken for an eel. The snake, with it’s passive nature is compelling viewing as it hunts amongst the crevices and cracks on the reef.  Watching them hunt and ascending to breath can be a diver’s delight.

Why not sign up for a   Underwater Naturalist Specialty Course, to learn more about the identification of species to enhance your knowledge and highlight the key things to look for or a go look for yourself on board MV Scuba Adventure or MV Scuba Fun.