xxwe

Our last holiday before returning to the UK from my assignment to Japan was a diving holiday in Thailand. We booked a week aboard the Aggressor Liveaboard with the aim of diving in the marine parks in the Southern Andaman sea. This was our first liveaboard and so we were pretty green and did not know what to expect.

Unfortunately the marine parks were closed and so we did not get to visit the better dive sites. What was worse was the captain did not tell us the situation until half way into the trip and we started to ask why were we visiting the same sites and why had we not got to the marine park. Any way we still got to do a lot of diving and the group bonded fairly well. We took some great underwater photos and I have grouped them below by the types of marine life they relate to;

Christmas Tree Worms

 I loved seeing these, probably nearly as much as nudibranches! The common name for these worms is derived from their appearance. Each worm has two brightly colored crowns that protrude from its tube-like body. These Christmas tree-like crowns are composed of radioles, or hair-like appendages radiating from the worm’s central spine. These appendages are used for respiration and to catch dinner, which typically consists of microscopic plants, or phytoplankton, floating in the water.

These worms are sedentary, meaning that once they find a place they like, they don’t move much. In fact, while the colorful crowns of these worms are visible, most of their bodies are anchored in burrows that they bore into live coral. When startled, Christmas tree worms rapidly retract into their burrows, hiding from would-be predators. This made it quite a challenge to photograph them especially with an underwater flash!

I have also included some photos of feather duster / fan worms. These are tube worms with a fan crown that traps plankton and moves it to the worms mouth.

Nudibranches

Link to an article describing different types with some identifying photos (Press Link)

Nudibranches are part of the sea slug family. Their scientific name, Nudibranchia, means naked gills, and describes the feathery gills and horns that most wear on their backs.

They are carnivores that slowly ply their range grazing on algae, sponges, anemones, corals, barnacles, and even other nudibranchs. To identify prey, they have two highly sensitive tentacles, called rhinophores, located on top of their heads. Nudibranchs derive their coloring from the food they eat, which helps in camouflage, and some even retain the foul-tasting poisons / stinging cells of their prey and secrete them as a defense against predators. They

Nudibranchs are simultaneous hermaphrodites, and can mate with any other mature member of their species. Their lifespan varies widely, with some living less than a month, and others living up to one year.

I always enjoy spotting these and then trying to get them on film – not easy to hold still and get the critter in focus

Moray Eels

I did not realise but Moray Eels are a type of fish that has evolved to survive in small and narrow crevices. Unlike snakes they are totally scaleless. The reason they constantly open and close their mouths is to control a flow of oxygen rich water to pass over their gills which are located next to their mouths. This makes them look much more aggressive than they are. They identify prey through scent rather than vision. It was good to see a range of different types on our dives

Lionfish

Stunning to look at and quite large (adults grow to 18 inches) these fish are one of the top predators in many coral reef environments. They are active hunters who ambush their prey by using their outstretched, fan like pectoral fins to slowly pursue and corner them. They are slow moving and conspicuous and so rely on their unusual coloration and poisonous fins to discourage would-be predators from eating them

Stonefish and other Dangerous critters

Here I have included photos of a range Scorpionfish. These are masters of camouflage and can blend in so perfectly with their surroundings that their prey, predators, and even divers have trouble seeing them. They almost always sit perfectly still, on the sea floor, in their preferred habitat of coral and rocky reefs, and their colors are often a perfect match for the substrate. Some individuals have even been observed with algae growing on them. While this camouflage gives them further protection from predators, its primary purpose is to allow scorpionfish to ambush their prey. They eat other reef fishes and some bottom dwelling invertebrates, but they do not actively pursue these animals. Instead, they wait for dinner to come to them. Waiting for hours at a time, scorpionfish strike when their potential prey is less than their body length away. Their powerful jaws and large mouths create so much pressure that they are easily able to suck down their unsuspecting prey and swallow it whole.

I have also included a picture of a stonefish, which is the most venomous fish in the sea and through their dorsal fin spines can inject venom which is fatal to an adult human in about an hour. Definitely something not to accidentally stand or lie on. There are several features that both fish share, but several that distinguish the two. Stonefish disguise themselves very well by burying themselves in the sand (looking like a rock, hence the name stonefish) while scorpionfish have fantastic camouflaging ability and are able to replicate the pattern of their surroundings.

I have also included a photo of a crown of thorns starfish which are considered a problem for healthy reefs given they attack coral. As well as a sea urchin

Shrimps and crabs

Soft and hard corals

Clownfish (nemo)

Clownfish are part of the family of damselfish that have a symbiotic relationship with sea anemones. the anemone protects the clownfish from predators as they dart in and out of the poisonous tentacles whilst providing food in terms of scraps eft from the anemone’s meals as well as a safe nesting site. In return the clownfish defends the anemone from parasites / predators and provides nutrients from its excrement which promotes the algae incorporated into the tissue of the anemone – critical for its growth and regeneration. A complex relationship.

Interestingly clownfish start off as males and when they mature they become females. Only 2 clownfish in a group reproduce. When the female dies then the ranking male turns into a female and the largest juvenile in the group becomes the breeding male after a period of rapid growth. So the colony within a single anemone usually consists of the reproductive male and female and a few male juveniles which help tend the colony and look after the eggs.

Giant Clams

Giant clams have been hunted for their meat and have become extinct in many areas where they were once common, so it was a treat to see these few examples and also be able to take photos of them with their mantles open as they quickly shut when surprised, ie divers approach, lights shine on them etc.

xx