Things You Didn’t Know About Your Favourite Critters
Few people know that male blue-ringed octopuses can’t tell the difference between males and females. When it comes to sex, they try to mate with any other blue-ringed octopus they meet. Name : Blue-ringed octopus (Hapalochlaena)
Family : Octopodidae
Size : They generally measure between
12 and 20 centimetres. The smaller, more common Hapalochlaena maculosa species weighs only about 28 grams Habitat : Often sighted in tide pools and coral reefs in the Pacific and Indian Oceans, from Japan to Australia, at depths of up to 50 metres. They can also be found among clumps of sea squirts, particularly after storms
Behaviour : The blue-ringed octopus diet typically consists of small crabs and shrimp.
They also tend to take advantage of small injured fish if they can catch them
A male blue-ring will pounce on any potential partner and insert their hectocotylus (scientific slang for “penis-arm”) into the mantle cavity of the other octopus. It’s only at this point that the male finds out if he hit the jackpot or got himself into a rather embarrassing situation. If the partner turns out to be another male, they amicably part ways, no harm done. In case he gets lucky and his partner is a female, the male clings on for as long as possible, only breaking contact when she forcefully removes him. This strategy is not without risk, since females occasionally attack, or even kill and eat the male during sex. The actual deed can take up to four hours, but I think we can all agree it hugely lacks in romanticism.
Few people know that male blue-ringed octopuses can’t tell the difference between males and females. When it comes to sex, they try to mate with any other blue-ringed octopus they meet.
SEAHORSES MAKE NOISE
Next time you encounter a seahorse, instead of just looking, you might want to listen too. One of the more quirky things all seahorses do is make noise, quite a lot of it even. Seahorses make two distinct types of sounds: “clicking” and “growling”. “Clicking” is used for interactions between seahorses, such as courtship or mating. “Growling” is a stress response when they are threatened or even captured by predators. It is thought that it might serve as an escape mechanism that startles predators. I absolutely love the idea of a growling seahorse!
Maybe because those predators would be laughing too hard after hearing a seahorse growling at them? So seahorses not only serenade their partners to get them in the right mood, they also growl to chase away predators. Strange little critters indeed. Name : Pygmy seahorse
(Hippocampus bargibanti) Family : Syngnathidae
Size : Can grow up to 20 millimetres
Habitat : Found in coastal areas ranging from southern Japan and Indonesia to northern Australia and New Caledonia Behaviour : Adults are usually in pairs or clusters of pairs. These groups can be as large as 28 pygmy seahorses on a single gorgonian at depths of 10 to 40 metres. As with other seahorses, the female lays her eggs in a brood pouch in the male’s trunk area and he carries the young
Most of the time, flamboyant cuttlefish are anything but flamboyant! In their standard state, flamboyant cuttlefish are a mottled grey, brown or black colour, blending in perfectly
with their sandy habitat
ARE NOT REALLY FLAMBOYANT...
When hearing the words “flamboyant cuttlefish”, you are likely to picture a cute, tiny multicoloured cuttlefish, flashing its waves of colour at you. You’re in for a surprise though. Most of the time, flamboyant cuttlefish are anything but flamboyant! In their “standard” state, flamboyant cuttlefish are a mottled grey, brown, or black colour, blending in perfectly with their sandy habitat. They usually only display their vivid colours when they are disturbed, hunting, or mating. Some divers might be tempted to disturb the animal to get more colourful pictures. Clearly this will stress the cuttlefish and should be avoided at all costs. Be patient instead. Observe it for a while and you might even be rewarded by seeing it hunt small shrimp, lay eggs, or even mate! Name : Metasepia pfefferi
Family : Sepiidae
Size : Can grow up to eight centimetres
in mantle length
Habitat : They inhabit tropical Indo-Pacific waters off northern Australia, southern New Guinea, as well as numerous islands in the Philippines, Indonesia and Malaysia.
They are mostly shallow-water animals, and can be found at depths of three to 86 metres
Behaviour : Active in the day, it hunts fish and crustaceans. Arm tips often display red colouration to ward off predators
Lures seem to mimic the fluorescence of free-swimming worms,
which are often eaten by small fish like cardinalfish, which in turn are
a tasty snack for the frogfish
...BUT HAIRY FROGFISH ARE (AT LEAST THEIR LURES)
You might have been lucky enough to have gone for a fluorescent night dive but few people have seen hairy frogfish while “fluo” diving.
It is worth a try though, if you want to see something truly special. The bodies of hairy frogfish do not fluoresce, but their worm-like lures do. Frogfish use their lure as a fishing rod, attracting small fish closer, which are then eaten whole. The fluorescent lures of hairy frogfish might be used to increase their hunting success.
They seem to mimic the fluorescence of free-swimming worms, which are often eaten by small fish like cardinalfish, which in turn are a tasty snack for the frogfish. By mimicking the fluorescence of these worms, frogfish might increase their chances of attracting and catching prey. Your next “fluo” dive might give you an exciting glimpse into previously unknown hunting strategies in the ocean. Name : Hairy frogfish (Antennarius striatus)
Family : Antennariidae
Size : Can grow up to 22 centimetres long
Habitat : Tropical Pacific, Eastern Atlantic, Eastern Pacific, Hawaii (Kona), Indian Ocean, Japan, Red Sea, Tropical Australia, Western Atlantic, Indonesia and Asia
Behaviour : These frogfish come in different varieties, often striped or with hairy appendages. Also known as anglerfish, they are lie-in-wait predators. They are equipped with a specialized lure called an esca, which it dangles in front of its head, ready to gulp down attracted prey
Frogfish are not the only critters with special hunting techniques. Wonderpuses have been seen bullying other octopuses to get a good feed. In at least one case, a wonderpus tried to asphyxiate a mimic octopus to steal its food! In fact, “constricting” is not uncommon in octopuses. They will use one of their many arms to plug the other octopus’ funnel (i.e., breathing hole). This makes it hard for the other octopus to breathe, but also prevents it from squirting ink. Not being able to ink might seem less important than breathing, but inking is used for more than just hiding from predators. Octopus ink often contains chemicals that act as an irritant for predators, making it even harder for the predator to get a meal of octopus. Octopuses don’t just constrict other octopuses to steal their food. Females sometimes do it during mating to kill and then eat their mate. Finally, it can be used as a defence against predators, for example by blocking the gills of sharks that try to eat the octopus.
Nudibranchs occasionally indulge in mating aggregations
(a nicer word for orgies), S&M (most of their penises have backward pointing spines), mating with different species
than their own, and in some species, adults mate
If you thought the sex life of octopuses was special, check out that of nudibranchs. To some extent their life is simpler. There are no males or females; instead nudibranchs are both at the same time. If that’s not special enough for you, here are some other things nudies get up to. Nudibranchs occasionally indulge in mating aggregations (a nicer word for orgies), S&M (most of their penises have backward pointing spines), mating with different species than their own (“any nudie is a good nudie”), and in some species, adults mate with juveniles. In what is probably one of the most bizarre cases of sex on the sand, a species of Siphopteron slugs uses a part of its forked penis to stab their partner through the head during mating! As if that wasn’t enough, they even inject prostate fluid into the head as well. Researchers have suggested this process (called “cephalo-traumatic secretion transfer”) might change the behaviour of the receiving slug. Go figure…
ABOVE: Blue-ringed octopus in Lembeh Strait, IndonesiaIMAGE: Maarten De Brauwer
ABOVE: Seahorse in Lembeh Strait, IndonesiaIMAGE: Maarten De Brauwer
ABOVE: Flamboyant cuttlefish eating a Randall’s pistol shrimpin Lembeh Strait, Indonesia
ABOVE: Hairy frogfish in Lembeh Strait,Indonesia
BELOW: Wonderpus in Bali, IndonesiaIMAGE: Maarten De Brauwer Name : Wunderpus photogenicusFamily : OctopodidaeSize : Can grow up to 30 to 45 centimetres from arm tip to arm tip; mantle (body) around 2 to 5 centimetres, occasionally larger Habitat : Lives in a burrow on the ocean floor.Found in shallow waters from Bali and Sulawesi, north to the Philippines and east to VanuatuBehaviour : Emerges to feed at dusk and at dawn.Moves by swimming or by using its arms to perform a walking motion over ocean floor. Feeds on fish and crustaceans
LEFT: Nudibranch in Lembeh Strait,IndonesiaIMAGE: Maarten De Brauwer
Name : Nembrotha kubaryanaFamily : PolyceridaeSize : Can grow up to 2.5 to 12 centimetres long Habitat : Found in the tropical Western Indo-Pacific Behaviour : It uses the toxins in its prey ascidians to defend itself against predators. It stores the toxins in its tissues and then releases them in a slimy defensive mucus when alarmed
MAARTEN DE BRAUWER is a marine biologist based in Curtin University at Perth, Australia.His recent research focuses on soft sediment habitats and cryptic species in Southeast Asia, but he is passionate about critters all over the world. The aim of his research, writing, and photography are to share the beauty of the ocean and help protect it for future generations.