Invertebrates, Fish, and Reptiles

Phylum Cnidaria 

Subphylum Medusozoa: 'Sea-jellies'

(Prince Frederick Harbour, Western Australia)

Some species of jellyfish swim up river to breed. In areas with large tidal ranges, the outgoing tide may resulting in jellyfish hanging from mangrove tree branches like plastic bags.

Phylum Arthropoda

 Class  Malacostraca

Order Decapoda

Family Ocypodidae

These are the crabs that have their eyes located at the end of stalks.

Uca spp. 'Fiddler Crabs'

Small and usually colourful crabs. The adult males have one enlarged claw that they wave around to establish territory, fight other males, and attract females.

(Prince Frederick Harbour, Australia)

Uca flammula, 'Flame Fiddler Crab'.

Class Insecta

Family Culicidae: Mosquitoes

The author getting bitten by a mosquito that is filling up my blood (image by Damon Ramsey)

When a mosquito bites a human, they are inserting a long section called a stylet into the skin to draw out the blood. Like other flies, only the female bites, as she needs the blood to produce her eggs. Different mosquitoes attack different species of vertebrates, including frogs, birds and mammals. Particular species of Culex attack mainly birds, while others in the genus Aedes attack mammals. Some mosquitoes inject a compound through their saliva which reduces blood clotting; this is what often causes the bites to itch later on. The bite in the image above...still itches.

Phylum Chordata

Superclass Osteichthyes: Bony Fish

Class Chondrichthyes

Family Dasyatidae: 'Whiptail Stingrays'

(Swift Bay, Western Australia)

Himantura astra, 'Black-spotted Whipray'. A dark ray with black, grey or off-white spots. Lives in sandy shallow waters around northern Australia and southern New Guinea.

Family Gobiidae

This huge family contains mainly smaller fish, particularly around the coral reefs, but they mostly lie motionless and generally go unseen. However, a (or several), small subgroups of the gobies have evolved into the mudskippers.

Subfamily Oxudercidae: 'Mudskippers'

There are over 40 species of mudskippers. They are found along the coasts of the tropical Indo-Pacific, from eastern Africa, through Asia and into the Pacific. They are not found in the Atlantic, except for one species that occurs on the western coast of Africa. They are absent from the Caribbean.

Mudskippers are surely one of the most amazing groups of all fish, spending much of their time out of the water. They are truly amphibious, living partly in and partly out of the water. Different genera have varying levels of adaptation to living either in or out of the water.

They are referred to as ‘mudskippers’, as they do indeed skip across the mud, with a flick of their tail. They also drag themselves along with their well developed and strong pectoral fins.

Another remarkable feature associated with their amphibious lifestyle are their bulbous eyes. These are huge for the size of the fish, and sit atop their head, giving them the potential for almost 360 degrees view. This helps them keep watch for movement of potential predators, such as kingfishers and egrets. The eyes can be completely sucked back into the eye socket to keep them moist.

Mudskippers also have bimodal respiration, which means they can breath both in the water (with gills) and in air. When on shore, like the unrelated frogs, they can perform cutaneous respiration, breathing through the skin, and through the lining in their mouth and throat. This requires that they stay moist, so mudskippers are never too far from water, and which is why they may be seen to occasionally roll in puddles. They also inflate the opercular chambers with air and so look like they have huge ‘chipmunk-like cheeks’.

(Hunter River, Prince Frederick Harbour, western Australia)

Mudskippers often set up and maintain territorial 'ponds', excavated circular pools in the mud. They can leap up from their pools of water in the mud to display to one another, jumping up to 60cm in height. They usually lay their eggs in a burrow. Because these burrows are often located in very low oxygen waters and soils, the fish take a pocket of air in the burrow. This has also been theorized as a preadaption that allowed mudskippers to evolve a lifestyle on the shore and out of the water.

Boleophthalmus spp., ‘Blue-spotted mudskippers’

(Hunter River, Prince Frederick Harbour, western Australia)

There are 5 species in this genus. They have comb like teeth for grazing on diatoms, cyanobacteria and green algae, which they feed on with a side to side movement. Males have territorial disputes by opening their mouths and pressing them against one another as if they are kissing. The males leap into the air to attract females, which they then invite into their burrows to spawn.

(Hunter River, Prince Frederick Harbour, western Australia)

Boleophthalmus caeruleomaculatus'Blue-spotted Mudskipper'. A large mudskipper with blue eyes and blue spots across flanks.

Family Monodactylidae: 'Diamondfish', 'Moonyfish'

(north-west Australia)

These fish are named due to their diamond shape and slivery glint. As they turn just near the surface, they often reflect the sunlight with their scales. They normally live around rocky areas or jetties in estuarine areas along tropical and subtropical coasts of the Indo-Pacific.  


Order Crocodilia: ‘Crocodiles’ and ‘Alligators’

Crocodilians are an easily recognizable group with distinctive features. They are large and long, with relatively short limbs, thick and strong tails. Their long snouts are full of sharp conical teeth. While the internal genetic differences between species of different crocodiles and alligators have changed over evolutionary time, their external physical differences have not varied as much; this retention of form suggests that their ‘design’ is a successful one without need of modification. And they have existed in this general form for at least 200 million years. Despite their antiquity, they are often seen as one of the more advanced of the ‘reptile’ groups. For example, they have a 4-chambered heart, like birds and mammals in some ways, and unlike the other reptiles. They also show some careful maternal care of the eggs, and even the hatchlings for a short time.

(Red Cone creek)

Crocodiles use different senses to interact with their environment and detect prey. As they hunt mostly at night, their eyes are sensitive to light. As with many nocturnal animals, after light passes through the front of the eye, it is reflected back by a layer of guanine crystals in the tapetum at the rear of the eye, to allow light another pass. This also causes the orange-red ‘eyeshine’ of crocodiles when spotlighted at night. Crocodiles have sealable nostrils at the end of their snout, through which they can smell carrion. Their eyes and nostrils are often the only part of the animal exposed when they are in the water. They are also have amongst the best hearing of any reptiles, being able to detect a wide range of frequencies.

(Prince Frederick Harbour, Australia)

Crocodylus porosus, 'Indo-Pacific/Salt-water Crocodile'. Biggest crocodilian in the world, also largest of all living reptiles. Also known as ‘Estuarine Crocodile’ or ‘Indo-Pacific Crocodile’, the first name reflecting its preferred habitat of estuaries, and the latter name reflecting its large geographical range throughout tropical Asia and the Pacific.

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