fT1 I o look like you I something are not I. is one o[ the animal kingdoms greatest adaptations for survival. To be inconspicuous within one's surroundings, or to mimic another speciesthat is harmful or unpalatable, is often the key to an animal's success, especiallyin the sea.Mimics may wish to hide from predators, or to render themselvesinvisible to the creatureson which they feed. Others are highly visible and encourage their prey to Marine Park northwardsis the false service that is respectedand sought come to them. cleanerfishlAsp idont us toenia tus).Thts after by many of the reefs inhabitants. Whether you dive in the Rowley fish mimics the cleaner wrasse The false cleanerfish,however, is not ShoalsMarine Park in the north, or in lLabroides dimidiatus). The real even a wrasse, but a blenny with the Archipelagoof the Recherchein the cleanerwrasse is a conspicuous,dainty enlarged fangs in its lower jaw. It Southern Ocean,if you look carefully, little fish, which darts around the resemblesthe cleaner wrasse almost you will find a mimic. Some fish have bodiesand headsof large,predatory perfectlyin shape,size and colour.Even taken on the appearanceand shapeof fish. Wth relative immunity, it can its juvenile stage displays the darker another fish species that is very enterthe mouthsand gill chambersof blue and broader black stripe of the successful at surviving. One such these predatorsto gently pick off y6ung cleaner wrasse. The blenny's speciesthat is found from the SharkBay parasites,thus providing a cleaning swimming motion also mimics the wrasse'sjerky movements. Fish that approach the blenny expecting an enjoyablecleaning session will suddenly losea chunk of skin, scalesor fin! A l€ssaggressive marine mimic is the saddleback leatherjacket (Paraluteres prionu/us). It looks like Valentin s pufferfish (Conthigaster ualentini) which, like all pufferfish, contains a deadly toxin in its flesh. Predators recognise this fish by its bright, distinctive markings, and avoid eating it. By looking like the pufferfish, the leatherjacketis mistakenfor the inedible species,and left alone.This tactic is also used by several species of fish that mimic the sabretoothblennies. As the name suggests,sabretooth biennies have large teeth in the lower jaw. They appear to be used mainly for defence. If you look like a sabretooth,predators are more likely to leaveyou alone. a PreDiouspage I Thevenomous stonefish look for all the I world like a rock,especially as it remains remarkablystill for long periods. l,46ouerThe seawhip gobyaligns itself | flatagainst Lhe sea whip. Often. ils eyes I arethe only partsthat give it away. l,l-ert Are theseValentin's pufferfish or I saddlebackleatherjackets pretending I to be the inediblepufferfish? The leatherjackethas a dorsalspine, but it is oftendifficult. to seeif it is [ai( flat on the back. Photos- Ann Storrie 50 ^*scora BLENDINGIN its head, mouth and the top of us brightly coloured with what is often Unlike fish that copy other fish, body protruding above the sand. Its calleddisruptive coloration. The colours most mimics use camouflageto blend swivelling eyes sometimes reveal its are designed to match the sponges, 'Ine into their surroundings.Many fish look presenceto perceptivedivers. ascidians and algae of the reei The similar to plant leaves,algae, corals, stonefishmay remainburied and almost mottled patterns also help to break up sponges or rocks. The estuarrne motionlessfor daysat a time, and it can the fish's outline. Many scorpionfish stonefish (Sgnanceja horrida), with its evenskip breathwhen prey approaches. possessfleshy extensions,or weed-like venomous spines, occurs from tne When it strikes, it does so with a appendageson their bodyand fins. Thrs Shark Bay Marine Park northwards.It remarkably swift, upwards movement givesthem an irregular texture like the blendsinto the reef so well that it is that takesthe prey totally by surprise underwatersurface on which they rest. rarely seenby divers,and unfortunately Like the stonefish,all members of Someare very common in the Marmion for the diver or wader,it is sometimes the scorpionfishfamily blend into their MarinePark and around RottnestIsland. trodden on. These stonefish have a surroundings. Many, however, are The large western red scorpioncod tough, warty skin that resembles rocks and rubble. Their skin secretesa sticky mucous to which sand,mud and silt adheres, thus enhancing its camouflage.In addition, the stonefish often partially buries itself, with only l,46ouerThis flounder can barely be f distinguishedfrom the seafloor. lAboue right: Glauert'sanglerfish is so I similarto a spongethal divershave even I pokedit andnot recognisedit as a fish. Ironically,it canengulf prey faster than anyother vertebrateon Earth. I Rrghf The westemred scorpioncod is I verycommon in localwaters. but it is not I alwayseasily seen on the colourfulreef. Photos AnnStorrie r,u,toscopo5l (korpomo sumpfuosa), for example,can perch on top of the reef,yet remain almost invisible to its prey and passingdivers. It is alwayswise to watch where you placeyour hand if resting it on the reef. Flatheadsare bottom-dwelling fish that spendmost of their time lying on the seabed,buried under a fine layer of sandor silt. Along with this protection, flatheadspossess special pigment-laden cells called chromatophores.These are found in the skin and enablethe fish to change colour to suit the underwater surfaceupon which they land.Flatheads alsohave a specialmembrane over their eyes.It is a mottled, weblike net that helps to camouflagethe ey€s, which protrude from the sand to watch for prey.This beautiful membraneis like a fingerurint in that it's pattern is unique to eachfish. Floundershave evolved a uniqueway to watchtheir preywhile lyingon their side. These fish bury themselves on their side,which is almost flat and easy to coverwith sand.Most fish, of course, haveeyes on either side of the head.So do the larvae of flounders and other flatfish. As the larva matures,however, one of the eyesgradually moves either around, or through, the head. The result is that both eyesend up on the sameside of the body.Some species have eyeson their left sides,others on their right. When the flounder burres itselfwiththe eyesside up, itstwo tiny, beady eyes swivel in all directions to watch for both prey and predators. SPONGEOR SILENT PREDATOR? One of the most highly evolved examples of mimicry is seen in the anglerfish. Glauert's anglerfish is sometimes seen under the Busselton lTop left: Flatheads,likeflounders. bury I themselvesin the sandand are a I similarcolour to theirsurroundings. lCentre left: Evenwhen pipefish are in I the openwater, they are still quite I difficult to seewhen closeto the reef, asthey areso thin. Photos- Ann Storrie | /-eft Unlessyou look carefully,the I leafyseadragon looks like a pieceof I floatingseaweed. Photo- Peter& MargyNicholas/Lochman Tlansparencies 52 turot"o"u Jetty.Its colour,texture, behaviour and structureso perfectly resemble a sponge that divershave been known to pokeand prodit, andstill not recogniseit as a fish. The anglerfishcan be bright orange, yellow,black or almostany colour to malchthe surrounding sponges. lts skin ispitted with largeand small cavities like a sponge,and its modifiedfins resemble little feet and stabiliseit on the reel Thesefins are often coveredwith a growthof algaeto aidcamouflage. As their namesuggests, anglerfish attracttheir prey with a lure.The lure is an extensionof the first spineof the dorsalfin, andit is like a tiny rodwith a 'bait', knownas the esca,on the end. Eventhe escalook likesomething that it is not. In our local angledish,it resemblesa piece of floatingtissue, but other specieshave escasthat mimic polychaeteworms, shrimps or tiny fish. The anglerfishmanipulates the escato simulatethe natural swimmingmotion of the creaturethat it mimics.When the prey approachesto take the lure, the anglerfish opens itj enormousmouth and sucls the prey in. Mostanglerfish Seadragonsare fish with tube-like I Thesponge-like appearance of the canenlarge their mouthby a factorof 12, snouts and bony plates, instead of I anglerfishmakes it easierto tempt I andcan do in scales,on their bodies.They have many preywith its danglinglure. so aboutsix milliseconds. Photo- AnnStorrie The negativepressure created by the leaf-like appendagesthat resemble expansionof the mouth and gill cavity seaweed.The leafy seadragonhas suck water and prey in. This givesthe evolved to such perfection that disturbit, or take it to the surfaceto anglerfishthe distinctionof beingthe sometimessmall fish will hide among showyour ftiends. Its swimbladder may fastestvertebnte predator on Earth! them, mistakingthem for weed.The rupture.Of course,if you do find one, dragonsdrift nearreal seaweed, gently you are amongvery few lucky divers. BODY 'Ibke POSTURE floatingback and forth in the current. who haveseen one in thewild. the Body posture is used by some Buoyancy control is thus very time to marvel at its shape,form and speciesto mimic their surroundings. important,and these fish must fill Lheir movement.Watch as its tiny snout darts Thefish assumesa positionthat makes swimbladders with air fromthe surface forwardto catch small shrimpsand it less likely to be seen againstits whenthey first emergefrom the egg. other planktonicanimals. But if you background. Pipefish are good Like all membersof their family, takeyour eyes off it for a second,it will examples.Some speciesswim in a seadragonmales carry and incubatethe vanishin the weed.The Ieafu seadragon vertical position,