Picking through rockpools
Tropical Queensland, Australia
27/02/21
A rock platform at low tide never ceases to be entertaining.
I originally set out to look for shallow-water corals, but the tide wasn't low enough. There was still plenty of life around though! I spent a few hours walking around lifting up rocks and poking through seaweed. The kinds of species here are so different to the ones found around Sydney despite being on the same coastline! I guess that's to be expected given the warmer climate, but it's a pleasant surprise. Somewhere along the way, Sydney's abundant Black Nerite snails (Nerita atramentosa) have given way to the numerous (and prettier) Polished Nerite snails (Nerita polita) found along tropical Queensland's coast. The unique Neptune's Necklace (Hormosira banksii) is nowhere to be seen, and even the seemingly similar Padina fraseri has turned into mats of Padina australis.
Gymnothorax pseudothyrsoideus
Highfin moray eel
A young moray eel. While they are hard to ID when this small, based on the head shape and slight blotching I believe it's a highfin. They grow to around 80cm. Unlike most fish, morays don't have gill covers, so must constantly open and close their mouth to push water over their gills.
Gymnothorax pseudothyrsoideus
Highfin moray eel
Another photo showing their sharp teeth. Moray eels actually have two separate sets of jaws - the second set, called pharyngeal jaws, reside in the throat, and are used to pull prey inside after the initial capture.
Onchidiidae sp.
Onch slug
A very cool air breathing sea slug. The look like limpets and have the same kind of suction mechanism so they don't lose water at low tide.
Arachnoides placenta
Cake sand dollar
A burrowing sea urchin that lives in sand eating detritus and algae. A thin layer of velvety flesh covers a hard plate-like skeleton called a test. This is a relatively small species of sand dollar, growing to around 6cm.
Aipysurus laevis
Olive sea snake
One of the joys of tropical rockpooling is finding reptiles right on the shoreline - this highly venomous sea snake was taking a nap under a rock. They spend most of their time hunting around sheltered coral areas for fish and crustaceans, surfacing every half an hour to breathe.
Chelonia mydas
Green sea turtle
A shallow water sea turtle that mainly inhabits seaweed-rich coral reefs. The somewhat confusing name comes from the layer of fat underneath the shell, which is coloured green by their seagrass diet. They likely gained this name during the period sea turtles were hunted and eaten. They can often be seen sunbathing for warmth or napping in the shallows.
Mauritia eglantina
Eglantine Cowry
While other snails use their shells to protect their soft bits, cowries do the opposite! They cover their shell with their mantle to repair it and prevent hitchhikers like barnacles clinging on for a ride.
Alpheus euphrosyne
Green Snapping Shrimp
An amazing creature that uses its larger claw to 'snap', creating a loud and intense shockwave. They do this to either scare away predators or to instantly kill or knock out its prey. They hide out in burrows under rocks waiting for food to pass by, and are usually more active at night.
Holothuria leucospilota
Black Sea Cucumber
Some sea cumumbers, like this one, can discharge stringy, sticky organs called cuvierian tubules from the base of their respiratory tree in self defence.
Holothuria leucospilota
Black Sea Cucumber
Like other echinoderms including starfish and sea urchins, sea cucumbers move around on tube feet with suction pads.
Capillaster multiradiatus
Many-rayed Feather Star
A large crinoid growing to about 20cm with around 20 arms as well. They can be found in a range of colours from red to cream but are usually black or brown. Like most feather stars, they attach themselves to structure with their cirri ('legs') and filter feed from the water column by waving their arms around.
Chelmon rostratus
Copperband butterflyfish
One of the most popular and sought after marine aquarium fish, this tropical butterflyfish spends its time swimming around shallow reefs looking for invertebrates. Their long mouths are perfect for poking into crevices to find shrimp, worms and even anemones to eat.
Valenciennea muralis
Mural Glidergoby
A social goby that is normally found in pairs on sandy lagoon flats. They are sand sifters, finding their food of microinvertebrates by gulping a mouthfull of substrate, and filtering the non-edible sand out of their gills.
Enneapterygius atrogulare
Ringscale Triplefin
A species that will always be hiding and clinging to structure. This is the drabber female - males are bright red and black. They can be aggressive and territorial, even pecking out the eyes of other fish that come too close!
Epinephelus coioides
Orange-spotted grouper
Like most groupers, these ambush predators are slow-moving and sedentary, usually waiting for food to swim near enough to suck in. They will eat anything from fish to crustaceans and worms. At night they generally hide, burying themselves in sand or mud.
Epinephelus quoyanus
Longfin grouper
A similar grouper species in the same genus, but only growing to a third of the size - to about 40cm. They are sequential hermaphrodites beginning life as females which mature at 24cm and then transition into males at around 33cm. Their long fleshy pectoral fins are used as supports for sitting on the substrate.
Ostorhinchus limenus
Sydney Cardinalfish
A shy, nocturnal fish that hides under ledges during the day, where several fish usually hover together in a loose school. They are mouthbrooders, with males carrying the fertilised eggs in their mouths for protection from predators.
Ellochelon vaigiensis
Squaretail mullet
A very common species in the shallows, with juveniles inhabiting most rockpools. While they vary in colouration across their range in the Indo-Pacific, juveniles usually have dorsal blotching and horizontal stripes on the lateral flanks. Generally herbivorous, these schooling fish can follow the tide all the way up a river into freshwater looking for algae.
Stegastes nigricans
Dusky gregory
Typical of fish in the Pomacentridae family, this damselfish will become aggressive and territorial when it grows up. This very special fish practices agriculture, growing a territory of edible algae which forms much of its diet. They can only digest certain species, and diligently weed out unwanted algae from their 'farms'.
Salarias fasciatus
Lawnmower blenny
A tropical combtooth blenny, this popular aquarium fish is known for eating algae by scraping it from rocks. They will however also eat most things other they come across like microinvertebrates and detritus. While they are able to change their colour to blend into their surroundings, these fish are generally brown and cream with a vertical mottling pattern.
Tetractenos hamiltoni
Common toadfish
This is a highly toxic shoaling pufferfish that lives in shallow coastal waters and estuaries. They will often bury themselves in sand with just the head exposed, waiting for food to drift by. When scared they can puff themselves up with air revealing short spines in the skin.
Abudefduf bengalensis
Bengal Sergeant
A social damselfish that can form large shoals around structure, particularly in shallow water and near the surf zone on rocky reefs. They can be distinguished from other Sergeant-major damsels by a slight white outline on their dorsal, anal and caudal fins.
Halichoeres miniatus
Cheek-ring Wrasse
This is the female of the species. As a protogynous hermaphrodite like most wrasse, if it becomes the dominant individual in its territory it will quickly change sex to become male. They are commonly found in amongst macroalgae and are one of the smaller representatives of their genus, growing to around 14cm.
Pseudolabrus guentheri
Gunther's Wrasse
A very bold wrasse that will investigate and eat anything meaty that it can smell out in their macroalgae habitat. They are particularly fond of crustaceans and have sharp canine teeth in both jaws which make short work of exoskeletons.
Siganus fuscescens
Black Rabbitfish
A herbivorous fish with a large appetite. They often school together and can change colour rapidly to their environment. The mottled colouration here is the sleeping/stress pattern. Their grooved dorsal and pelvic fins contain a potent venom similar in composition to that of stonefish.
Unfortunately, no sunset to end the day.