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.

8^th to 11^th DECEMBER 2011

Lucrezia, Rene, Guido and Gianna who had completed the previous trip to the Similans on board MV Scuba Adventure were joined by Thomas from Switzerland and Richard from Holland for the Southern trip. With supplies loaded we headed to Maya Bay, Phi-Phi where we spent the night. With the briefings completed we had our first dive on Koh Bida Nai. Captain Pu dropped us on the wall area. Amongst the group were many photo enthusiasts, so we took our time looking for macro critters on the wall area. Visability was good, so the schools of fish slightly into the blue were seen.

After breakfast we dropped in 2 groups on Koh Bida Nok as we used the dinghy. Again, the wall area was the highlight of the dive again looking for the nudibranchs, shrimps, lobsters, morays and anything that was photogenic! The sloping reef area with the carpet of anemones was home for mantis shrimps, giant morays and a school of yellow stripped snappers. The dinghy picked up the divers and unfortunately Jack, a crew member, went for an unexpected swim when he tried to get Kath out of the water.

We then headed to Koh Haa for our third dive of the day at the Cathedral on Koh Ha Yai. We dropped in directly in front of the caves. We entered cave 2 and then swam through the connecting hole into cave 3. Looking through the hole is quite a sight as the remaining divers swam through.  The light was incredible. Once in cave 3 the fun started with the photographers trying to get the silhouette shot in the cave entrance. Lucrezia was using her new camera and had some successful shots. In the swim through there was a beautiful nudibranch , which was the first of many on that dive. Going across the plateau through the whip coral garden and on to the boulder area with the beautiful soft corals was a pleasure.  The night dive was on Koh Ha Yai with Robert and Kath. The other customers decided to relax with a beer. The night dive was very tranquil and many different types of crab were seen, but the highlight was an anemone crab that was sat on top of a coral formation. Lion fish were out hunting and a giant free swimming moray gave a performance for us.

Day 2 was the highlight of the trip. The first dive was on Hin Muang otherwise known as Purple Rock due to the abundance of purple soft coral. Here we were not looking primarily for macro as the bigger picture is magical. The atmosphere on this dive site is an experience. With hardly any current it was easy to navigate without too much effort. The hunters were out and you could feel the tension as they circled the smaller fish.

The second dive was on Hin Deang, otherwise known as “Red Rock” as there are many red soft corals. Thank you to Richard, who drew the dive site map. With the sloping reef area and the vertical walls this dive site has a variety of topography. Again, a great dive with trevellies, emperors, rainbow runners, tuna and barracuda. At the end of the dive a thermocline came in as Kath, Richard, Gianna and Guido were heading to the safety stop. Then through a wall of damsel fish and fusiliers came the big boy….A whale shark about 5m in length. Richard was off like a rocket and managed to get the magnificent creature on video. Needless to say that the third dive of the day was on Hin Deang. During the briefing “X” marked the spot on the map where the whale shark had been spotted. When we descended we swam over to the area and there it appeared. Whale sharks are directional and unlike manta’s do not swim in circles, so we only had a few moments with it, but when seeing something of this magnitude every second counts!!

The 4^th dive of the day was a sunset dive on Koh Ha Neau. The current was very strong, so we were only able to swim around the rocks as it would have been endurance to get to the reef. Again we were on a mission to find macro. The boulders are covered in soft corals of different colours. This area also has many anemones that start to close at this time of day revealing their different colours including white, green, shades of blue and purple. At the end of the dive we swam up the chimney, which starts at 16m and finishes at 5m, an ideal place to do a safety stop. While we were waiting on the surface to be picked up by Captain Pu and the crew we saw a gorgeous sunset that was worthy of a photograph.  Back on the boat we headed to Phi Phi and Tonsai Bay where we went ashore for a couple of hours to have a few drinks on the beach and watch a fire show.

Day 3 and we decided that we would dive the wall not far from Maya Bay. A relaxed, chilled dive with plenty of fish and corals. We had the pleasure of a turtle towards the end of the dive. He was quite happy having his photograph taken and even posed for us!!! The last dive of the trip was on Shark Point. Good visability and little current made this one to remember. There was a promise of a Sea Horse and thankfully, Kath found it. Again, the photographers were in their element as we were the only divers on the site. The whole dive was on pinnacle one as there was so much to see. This beautiful dive site has varied marine life, huge barrel sponges, gorgonion sea fans and lots of soft coral. The scenery it’s self is stunning.

Once again, we had a fantastic trip.