Things You Didn’t Know About Your Favourite Crit­ters

Asian Diver (English) - - Feature Small Creatures, Big Value - By: Maarten De Brauwer

BLUE-RINGED OC­TO­PUS

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

FLAM­BOY­ANT CUT­TLE­FISH

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

OC­TO­PUS AS­PHYX­I­A­TION

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

with ju­ve­niles

REAR­ING NUDI

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

IMAGE: Maarten De Brauwer

ABOVE: Flam­boy­ant cut­tle­fish eat­ing a Ran­dall’s pis­tol shrimpin Lem­beh Strait, In­done­sia

IMAGE: Maarten De Brauwer

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.

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