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159. Broadclub Cuttlefish (Sepia latimanus)



Subject:

A female Broadclub Cuttlefish (Sepia latimanus) is depositing her eggs one by one in these hard coral formations on a shallow Balinese reef.


The Broadclub Cuttlefish is the second-largest species within the cuttlefish family, reaching a length of 50cm/20 inches and weighing up to 10kg/22lbs. This large cephalopod is a very commonly encountered species in the Indo-Pacific region because it shares the same interests for coral reefs as scuba divers and ventures to the same depths.


The Broadclub Cuttlefish's ability to change colour (all within the white, cream, yellow, and brown range) and skin structure make it a favourite subject among underwater videographers and photographers alike.


Breeding males, who are sometimes dark brown, are very territorial and defend a patch of coral. After mating, the females will lay their eggs in the corals defended and claimed by the male. Males perform various pre-copulatory skin patterns to attract potential female candidates for copulation. During copulation, the male grasps the female and inserts its hectocotylus (the male's specialised reproductive arm) into the female's mantle cavity, where the fertilisation of the eggs occurs.


The female will attach each individual egg underneath a branch of coral, as seen in this underwater video clip. The eggs are soft when laid but will harden soon after being deposited on the corals. Hatching happens after 38 to 40 days or so, after which the newborn cuttlefish, looking like an exact miniature copy of their parents, will mingle with the coral branches and rubble. Because they are subject to predation, they protect themselves by mimicking the dead leaves of fallen mangrove trees. The ability to change colour and skin texture makes them difficult to distinguish from real mangrove leaves. Like all other cuttlefish species, the Broadclub Cuttlefish is polyandrous, meaning that females often mate with more than one male. Immediately after mating with a male, the female will move on to another male and mate again. This may be repeated several times.


When the mating period is over, the cuttlefish will start to die. Their lifespan is around 14 to 18 months or so, unless they are eaten before they have the chance to reproduce themselves.


Cuttlefish are active hunters of small fish and crustaceans, and they seem to be hooked on prawns. The Broadclub Cuttlefish hunts with the aid of its changeable body colours. Rapidly changing and rhythmic fluctuating colours and patterns help to mesmerise, distract, and hypnotise their prey so that they suddenly strike and grab it with their two feeding tentacles and pull it into their mouths.


Cuttlefish are often preyed on by bigger fish such as groupers and sharks. Also, the Indo-Pacific Bottlenose Dolphin (Tursiops aduncus) is an active cuttlefish hunter.


Technique:

The footage was filmed around 10 years ago with a GoPro Hero 2. Although the little action camera was fitted with an orange filter, we had to correct the vivid and unnatural colours in post-production. This was due to the absence of a manual white-balance function on the small camera. Todays action cameras are equipped with a white-balance function.


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