Travelfish contributions by NickHope
The first number represents the total number of published reviews by NickHope. The bracketed figure is submitted reviews -- reviews may not be published for editorial reasons or may be removed because the property concerned has been delisted from Travelfish or has closed.
Travel map for NickHope
Life according to NickHope
An English filmmaker based in Bangkok. Mostly underwater.
Scuba diving trips to the Similan Islands, Gulf of Thailand, Burma, North Sulawesi, Bali and Malaysia.
Boonsung wreck off Khao Lak, then Anilao in the Philippines.
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Part 20, the final part of my documentary, “Mucky...
Published 1:26 am, 29 Aug 2014
Part 20, the final part of my documentary, “Mucky Secrets”, about the fascinating marine creatures of the Lembeh Strait in Indonesia.
The sap-sucking slug (Sacoglossa, sacoglossan) Elysia sp. is not a nudibranch. It does not have gills as such but breathes through two leafy flaps called parapodia that run most of the length of its body. The rhinophores on its head have a semi-tubular form. It feeds by sucking the fluid from green algae, and the chloroplasts it contains give the body a bright green colour which fades if the slug goes short of food. Behind the rhinophores it has tiny photo-receptors for eyes. The white spots are raised glands that can secrete a repellent white substance.
Headshield slugs (family Aglajidae, superfamily Philinoidea, clade Cephalaspidea) lack tentacles and most retain a small thin internal shell. They also have parapodia, which are wrapped up and around the body. Many excrete mucous to help them burrow into the substrate, and the headshield prevents sand entering the mantle cavity. The Gardiner’s headshield slug (Philinopsis gardineri) feeds on polychaete worms. And the pleasant headshield slug (Chelidonura amoena) feeds exclusively on acoel flatworms that infest hard corals and sponges. Small, dark eyespots on the front of its head give it very primitive vision.
Like the striated frogfish, the ragged sea hare (Bursatella leachii) is camouflaged with long papillae that help it disappear on a seabed strewn with algae. Sea hares (family Aplysiidae, superfamily Aplysioidea, clade Aplysiomorpha) get their name from the overall body shape and the long pair of rhinophores on the head, which are tubular, and give it an acute sense of smell. It also has a second pair of tentacles at the sides of the mouth and it gobbles up the thin layer of cyanobacteria that coats the seabed. Below the rhinophores it has a pair of tiny eyes. If it is disturbed it can release a noxious mixture of white opaline and purple ink. Recent research has shown that this sticks to the antennae of predators such as lobsters and dulls their senses. The bright blue eyespots covering the body are more vivid here than in populations in other parts of the world.
Ragged sea hares and the similar but smaller long-tailed sea hare (Stylocheilus longicauda) sometimes form huge swarming aggregations comprising hundreds or even thousands of individuals of varying size. They tumble over each other, devouring cyanobacteria and defecating as they stampede across the sea floor. In an aggregation they are an easy target for predators. Pufferfishes and predatory sea slugs have been seen to pick them off one by one. They breed quickly and have even been sold into the aquarium trade as “sea bunnies” for eating unwanted algae and providing food for other tank inhabitants with their larvae. It is said that inhabitants of some of the Cook Islands and Austral Islands collect and eat swarms of these sea hares, discarding the toxic internal organs. It is a mystery why sea hares aggregate like this. They have been observed to all mate, spawn and die at the same time.
Although they resemble sea slugs, polyclad flatworms (Polycladida) are quite different. The ruffled periphery of the glorious flatworm, Pseudobiceros gloriosus, forms a pair of pseudotentacles reminiscent of nudibranchs’ rhinophores. Occasionally flatworms leave the seabed to swim and when they do, they are a spectacular sight.
Part 19 of my documentary, “Mucky Secrets”, about...
Published 12:46 pm, 21 Aug 2014
Part 19 of my documentary, “Mucky Secrets”, about the fascinating marine creatures of the Lembeh Strait in Indonesia.
In this video we study how sea slugs (including nudibranchs) feed and mate.
All known nudibranchs are carnivores. The biggest family of nudibranchs, the chromodoridids, feed exclusively on sponges.
Most sea slugs have a ribbon-like tongue covered in microscopic teeth called a radula to help them consume their prey. The form of the radula varies greatly and is important as a basis for taxonomic classification.
We see a pleurobranch, Pleurobranchus forskalii, a different type of sea slug, feeding on an ascidian, or “sea squirt”, a type of tunicate.
Nembrotha nudibranchs also feed on ascidians. We see a Nembrotha lineolata feeding on a blue club tunicate. The ascidian feeds by filtering plankton from the water with its delicate, blue, sieve-like interior enclosed in a clear outer sac, its tunic. The sea slug everts its proboscis, its oral tube, out of its mouth and, with ruthless efficiency, sucks this fleshy interior right through the tunic. The radula teeth enable the slug to deal with the tougher parts of the sea squirt’s intestines.
Most sea slugs are quite specific in their choice of food, and so they are often drawn towards the same place. This increases the chances of encountering others of the same species and finding a mate. As they have no vision, nudibranchs locate each other initially through smell then touch.
During copulation, they line up their genitals which are on the right side of their body. All sea slugs are hermaphrodites and contain both male and female reproductive systems. During mating, each nudibranch receives sperm from the other.
We see a pair of Nembrotha purpureolineata nudibranchs mating. The penis, which is off to the side, is covered in tiny, sharp barbs which lock it into the vagina, which is at the centre of the stalk. The male organs often mature before the female ones. Small nudibranchs with an immature female reproductive system can store the sperm they receive until they start producing fertile eggs.
We also encounter a mating pair of Hypselodoris bullocki nudibranchs. Their genitals are also covered in tiny spines that anchor them together during copulation.
After fertilisation, a mucus-bound ribbon of eggs is laid in a spiral, often on or near the species’ food source. Most egg masses are toxic to predators and are abandoned by the parent.
Hypselodorid nudibranchs often follow each other around, top to tail. The reason for this ‘trailing’, or “tailgating” behaviour is a mystery. It’s thought to be a prelude to mating, but in some cases the trailing slug might simply be getting an easy ride in the search for food.
Part 18 of my documentary, “Mucky Secrets”, about...
Published 12:32 pm, 21 Aug 2014
Part 18 of my documentary, “Mucky Secrets”, about the fascinating marine creatures of the Lembeh Strait in Indonesia.
A huge and fascinating diversity of sea slugs, or opisthobranchs (Opisthobranchia), are found in the Lembeh Strait. Opisthobranch means “gills behind”, because their gills are located behind their heart.
Most sea slugs have all but lost their protective shell, but compensate with more advanced weapons of defence.
Over six thousand different species of sea slug are nudibranchs (Nudibranchia). The name means “naked gills”, referring to the rosette of branchial plumes on their back, surrounding their anus. These gills vary greatly in form, but all have a large surface area for oxygen exchange.
Part 17 of my documentary, “Mucky Secrets”, about...
Published 12:15 pm, 14 Aug 2014
Part 17 of my documentary, “Mucky Secrets”, about the fascinating marine creatures of the Lembeh Strait in Indonesia.
As we continue to examine molluscs (mollusks, Mollusca) in this documentary series, we take a quick look at the electric flame scallop (Ctenoides ales), otherwise known as the “disco clam”, “fire clam” or “electric clam”. The flame scallop is a type of bivalve (Bivalvia). It appears to emit luminescent electrical pulses, but actually it is rolling and unrolling the edges of its mantle, revealing special particles that simply reflect light. The display is thought to attract phytoplankton as food and perhaps frighten off predators like crabs and shrimps.
We then turn our attention to sea snail (gastropods, Gastropoda). The grey bonnet (Phalium glaucum) is a typical sea snail. It has a protective, coiled shell that it can withdraw its entire body into. It glides over the substrate on its large, muscular foot, and at the rear we see the operculum, a hard lid that is used to close the opening of the shell after the snail withdraws into it. Two simple eyes peer out from under the front of the shell, and important sensory feedback also comes from the two tentacles. To one side is the inhalent siphon, a tube that the sea snail uses to draw in water for respiration.
The anatomy of another gastropod, the vomer conch (Euprotomus vomer), is different. Its mouth is much more obvious, at the end of a long protrusion called a proboscis. It is strictly a herbivore, and it uses the proboscis for locating and eating algae growing in the sand. It’s eyes are much more prominent too, at the end of long stalks, and jutting out from these stalks are two highly sensitive tentacles. Rather than gliding, it uses its operculum to drag itself along the bottom in a lurching motion.
Conchs are a popular food, and their shells have symbolic and religious significance in some cultures. They have been used for everything from musical instruments, to weapons, to ink holders.
We then encounter a whitespotted hermit crab inhabiting an empty cone shell. The main sensory device of cones like the ivory cone (Conus eburneus) is the siphon itself which contains highly sensitive chemoreceptors. If it detects suitable prey the cone will unleash a harpoon from its proboscis containing a highly venomous neurotoxin, powerful enough to kill humans.
Part 16 of my documentary, “Mucky Secrets”, about...
Published 12:05 pm, 14 Aug 2014
Part 16 of my documentary, “Mucky Secrets”, about the fascinating marine creatures of the Lembeh Strait in Indonesia.
In this video I look at cuttlefishes (Sepiida) and octopuses (Octopoda); types of cephalopod (Cephalopoda) found in the Lembeh Strait.
The broadclub cuttlefish (Sepia latimanus) is the second largest species of cuttlefish, and the most common on coral reefs. It can adopt an infinite number of textures, colours and poses to camouflage itself, communicate and to hypnotize prey.
As the name suggests, the crinoid cuttlefish (Sepia sp.) tends to hang around feather stars. We find one hiding amongst the branches of a decaying staghorn coral. This is an undescribed species known only from Indonesia, and recognised by the dark spots at the front of its lower arms.
The dwarf cuttlefish, or stumpy-spined cuttlefish (Sepia bandensis) is a tiny species that is usually only seen at night. Rather than swimming, it usually uses its lower arms to walk on and explore the seabed. It is often found in association with echinoderms such as sea urchins.
Another species that walks on its arms is one of the real stars of Lembeh, the flamboyant cuttlefish (Metasepia pfefferi). When disturbed it abandons its camouflage and the skin adopts spectacular shades of purple and yellow, with waves of white radiating down the mantle. The colour changes are achieved by adjusting millions of pigmented cells in the skin called chromatophores. This is an example of aposematic coloration whereby a creature warns potential predators of its toxicity. Scientists have recently discovered that the flamboyant cuttlefish’s muscle tissue contains a unique and highly potent toxin, proving that this display is no bluff.
We see an adult flamboyant cuttlefish using its special feeding tentacles to snatch prey such as small shrimps and gobes, and a tiny juvenile raising its median tentacles, a common threat display amongst cuttlefishes.
Cuttlefishes’ intelligence and unique powers compensate for their lack of a protective shell. They have the highest brain-to-body-mass ratio of all invertebrates, and researchers have shown them to possess a good memory and a high capacity for learning.
Octopuses are closely related to cuttlefishes and have similar characteristics and intelligence.
At TK we encounter an undescribed octopus, a near relative of the mimic octopus and wonderpus, retreating to its burrow with a captured crab. The octopus usually injects the crab with a paralysing saliva before using it’s parrot-like beak at the centre its arms to excavate the meat from the crab.
Finally on a night dive at Aer Perang we encounter a starry night octopus, Callistoctopus luteus, twisting and turning around the reef as it tries to escape my attention.