Blue Devil fish live in exposed reef from 3-30m deep. They range from Montague Island NSW to the gold Coast in QLD. They range in length and can grow to a maximum of 40cms. Blue Devil fish are solitary creatures that usually live alone in caves or crevices during the day; it can sometimes be seen out roaming the reef at night. Usually they appear shy to divers, as they do not swim away fleeing when discovered, but tend to move to the very back of a cave or crevice to remain out of site.

The main reason you usually only ever find one Blue Devil Fish in a cave or under a ledge is that the male sets up his own territory in a cave or overhang in order to attract a mate. If there is more than one male around, one will drive the other away. Blue Devil Fish mate in spring. The eggs are glued to the roof of the cave until they hatch.

The Blue Devil Fish is now fully protected in NSW.

Nudibranchs

Nudibranchs are marine snails that have no shell (or in which the shell is significantly reduced). The largest species of nudibranchs grow to 40 cm, the smallest are easily able to move through grains of sand. Most are smaller than 10 cm.

'Nudibranch' means 'naked gills' because their gills are on the rear of the back of some species or along the side.

Most nudibranchs have a file-like organ (radula) which is only found in molluscs and is used to scrape off their food. This organ is covered on top with rows of teeth.

Nudibranchs have an amazing array of defences. Colour is believed to be an important defence in many species. Others ingest and utilise the stinging cells from soft corals.

Wobbegong Sharks

Wobbegong is the common name given to the eight species of carpet sharks in the family Orectolobidae. They are found in shallow temperate and tropical waters of the western Pacific Ocean and eastern Indian Ocean, chiefly around Australia and Indonesia.

Wobbegongs are bottom-dwelling sharks which spend much of their time resting on the sea floor, often among rocks or under ledges. The largest species, the spotted wobbegong, Orectolobus maculatus, grows up to 3.2 m long. Wobbegongs are well camouflaged with a symmetrical pattern of bold markings which resembles carpet. Wobbegongs make use of their relative invisibility to hide among rocks and catch smaller fish which swim too close, typical of ambush predators.

The Eastern Frogfish has a large mouth, fleshy lips and a tasseled 'beard'. It has a large head with raised eyes. The pectoral fins are large. The three short first dorsal fin spines are reported to be venomous. It grows to 30 cm in length. When captured, the Eastern Frogfish is capable of making a croaking sound.

It hides any where from very shallow waters down to at least 150 m in depth. It has been observed sheltering in holes on rocky reefs, kelp beds and silty areas.

Cuttle Fish

Cuttlefish are marine animals belonging to the Cephalopoda class (which also includes squid, octopuses, and nautiluses). Despite their common name, cuttlefish are not fish but mollusks. Recent studies indicate that cuttlefish are among the most intellegent invertebrates species. 

Cuttlefish have an internal shell, large W shaped eyes and eight arms and two tentacles furnished with denticulated suckers, with which they secure their prey

Cuttlefish eat small molusks, crabs, shrimp and other cuttlefish. Their predators include dolphins, sharks, fish, seals and other cuttlefish. Their life expectancy is about one to two years.

The Smooth Stingray also has a relatively short tail, less than 1.2 times the disc length. This gives the fish its species name, brevicaudata, which comes from the Latin brevis, meaning short, and cauda meaning tail.

The Smooth Stingray is not aggressive and is easily observed by divers. It usually has one venomous spine (the sting) halfway along the tail which is capable of inflicting severe or potentially fatal wounds. This species is sometimes observed raising its tail above its back like a scorpion.

The Smooth Stingray is a bottom-dwelling species which is recorded from temperate waters of Australia, New Zealand and South Africa.

In Australia it occurs from southern Queensland, around the south of the country and north to the central coast of Western Australia. It lives in coastal waters and estuaries from shallow water down to about 170 m.

Lion Fish

The lionfish is native to the tropical Indo-Pacific region of the world, but various species can be found worldwide. 

The common lionfish generally reaches a size of 30-35cm.

Lionfish have venomous spines that are deadly to their prey, but usually not to humans. If a human is envenomated, that person will experience severe pain and possible headaches and vomiting. A common treatment is soaking the afflicted area in hot water, as very few hospitals carry specific treatments. However, immediate emergency medical treatment is still advised, as some people may be more susceptible to the venom than others.

Lionfish are voracious predators. When hunting, they corner prey using their large fins and then use their quick reflexes to swallow the prey whole.

Rock Cod

Lotella rhacina

The rock cod  is a temperate fish found off the coasts of south eastern Australia, Tasmania the Great Australian Bite and northwards up the south western Australia coasts. They are also found around the coasts of New Zealand. They belong to the family Galidae are thus related to the true cods (genus Gadus). They are also known as beardie in Australia.

Rock cod are yellow-grey to red-brown with white fin margins. They have chin barbels. They may grow up to 50cm in length. They are found in caves in bays and coastal reefs. They are frequently found inshore and inhabit shallow waters in the continental shelf with typical depth of 10 to 90 metres.

Note that there are many other fish that are sometimes referred to as rock cod, but most of these are unrelated to the cod family, and are better known as gropers.

 weedy Seadragons can grow to about 46cm in length. The seadragon camouflage is quite good and they do resemble seaweed floating on the bottom of the sea floor. Unless you know what you are looking for seadragons can be easily overlooked. Once you have found a few of these creatures it becomes easier to spot them.

The seadragons diet mainly consists of sea lice and other small crustaceans. They seem to suck their prey straight into the snout! There is much concern for the future of the Weedy Seadragon and others in their family. They are threatened by habitat destruction.

The Port Jackson Shark, which can grow to 1.65 m. More commonly, however, the males grow to 75 cm and the females between 80 cm and 95 cm. When they hatch, juvenile Port Jackson Sharks, called pups, are about 25 cm long.

The family Heterodontidae is found in tropical and temperate marine waters in depths down to 275 m, although most are found in depths less than 100 m. The Port Jackson Shark occurs in southern Australian waters.

Port Jackson Sharks usually live in rocky environments on, or near, the bottom. Sometimes they are found in muddy and sandy areas, or where seagrass occurs. Their diet usually consists of sea urchins, molluscs, crustaceans and fish.

They forage for their food at night when their prey are most active, and often use caves and rocky outcrops as protection during the day.

Port Jackson Sharks are considered harmless to humans, although the teeth, whilst not large or sharp, can give a painful bite.

The Three-bar Porcupinefish has a rounded body that is covered with spines. The spines on the back are blade-like and fixed in position, but those on the belly and head can be raised. The teeth are fused to form a single plate in both jaws. It grows to 43 cm in length.

The Three-bar Porcupinefish is endemic to Australia. It is found on coastal and offshore reefs, often in rocky areas, from southern Queensland to northern Tasmania.

Boxfish

The boxfishes are a family, Ostraciidae, of squared, bony fish belonging to the order Tetraodontiformes, closely related to the pufferfishes and filefishes. They come in a variety of different colors, and are notable for the hexagonal or "honeycomb" patterns in their skin and skeletons. They swim in a rowing manner. Fish in the family are known variously as boxfishes, cofferfishes, cowfishes and trunkfishes.

The hexagonal plate-like scales of these fish are fused together into a solid, triangular, box-like carapace, from which the fins and tail protrude. Young boxfishes have a more rounded in shape and may exhibit bright colors. Because of their body scale structure, boxfishes are limited to slow movements.

Southern Blue-ringed octopus

Hapalochlaena maculosa.

The tiny Blue-ringed octopus, which, ironically for its size, is the most deadly of all cephalopods When alarmed, it displays small blue rings are small that generally measure less than 2 mm in diameter. It weighs only 28 grams with a body to 5 cm long and arms to 10 cm. The Blue-ringed octopus can be found only in the temperate waters of southern Australia, from southern Western Australia to eastern Victoria at depths ranging from 0-50 m.

The Blue-ringed octopus feeds on small crabs, hermit crabs, and shrimp that it hunts during the day. Two types of poison secreted by two separate poison glands are used against prey and predators. One of the poisons is used for hunting crab, the other, which is extremely toxic, is used as self defence against predators.

The Blue- ringed octopus is about the size of a pea when hatched then grows to reach the size of a golf ball as an adult.