Sea snakes

Sea Snake - Photo the Ocean Agency / Adobe

What is a sea-snake? Sea-snakes are cold-blooded reptiles, so they live mostly in warm tropical waters. Sea-snakes are fully adapted to breathe, feed, breed and grow in the sea. For air-breathing animals, sea-snakes are remarkable divers. Some species can dive to 100 metres or more, and remain submerged for up to 80 minutes. This may be partly due to the remarkable ability of some species to absorb part of the oxygen they need through their skins. Their nostrils have valves that close when they are underwater.

What do they look like? The 22 species of sea-snakes found in WA vary greatly in their colours and markings. They all, however, have nostrils on the top of the snout, a boat-shaped abdomen and a flat tail that acts as a paddle to help them swim more effectively.

Where do they live? Most sea-snakes live in the warm, shallow seas of the tropics and sub-tropics. Some inhabit muddy estuaries, while others show a liking for clear waters near reefs. Individuals of some tropical species are occasionally swept south by warm currents, but eventually perish in the cooler southerly waters. Sea-snakes are common in Shark Bay Marine Park, Ningaloo Marine Park, Montebello Islands Marine Park and Rowley Shoals Marine Park. The Shark Bay sea-snake (Aipysurus pooleorum) lives almost exclusively in the Shark Bay Marine Park. The yellow-bellied sea-snake (Pelamis platura) lives in the open ocean and sometimes washes up on beaches in the south-west.

What they eat and how: Sea-snakes inject venom with their bites to subdue and kill prey, which is then grabbed in the jaws and swallowed whole. As with other snakes, the skullbones of sea-snakes are loosely attached and they can dislocate their lower jaws and slide them sideways to allowing them to swallow very large prey. Sea-snakes tend to be fussy eaters. Some only eat catfish, another only eats the eggs of two families of fish. Others dine on eels, fish, prawns, crabs and worms.

Behaviour: Sea-snakes are quite curious and may approach people, but if you don't touch them they should leave you alone. Sea-snakes have been known to curl around divers' regulator hoses and limbs, especially during the breeding season (perhaps mistaking them for a female of their own kind). If this occurs, don't become alarmed, but wait patiently until they move off. Although sea-snakes are highly venomous, they are generally quite placid and rarely attack people unless provoked. Even if they do bite, they do not always release venom. As a precaution, however, never touch sea-snakes washed onto beaches, even if they seem dead. They may still be alive and lash out in alarm.

Breeding: Female sea-snakes sometimes attract attention from more than one suitor and mate in the open water. They give birth to live young at sea. The mother then leaves the young to fend for themselves.

Conservation status: No species of sea-snakes are listed as threatened, although the distribution and status of most species is not very well known.

Socials

Black browed Albatross on nest - Photo David / Adobe

Albatrosses

Albatrosses are perfectly adapted to spending most of their lives at sea and riding the air currents above the ocean.

Anemonefish

Anemonefish are exquisite little fish in the tropical damselfish family. They are popular pets in aquariums, and were the main characters in the animated Disney film Finding Nemo.

Australian pelican

Australian pelicans (Pelecanus conspicillatus) are large, black and white birds with massive pouched bills. The bird’s pouch is used mainly as a ‘scoop net’ for catching small fish and shrimps.

A baler crawls along on its enormous foot - Photo Suzanne Long DBCA

Baler shell

The Baler shell is a type of large sea snail that belongs to the gastropod family Volutidae.

Blue manna crab

The blue manna crab (Portunus pelagicus) is the only ten-legged crustacean found around the entire Australian continent.

Blue-ringed octopus

Blue-ringed octopuses are molluscs and, along with their close relatives the squid and cuttlefish, are the most highly developed invertebrates.

Butterfly cod

Butterfly cod are spectacular fish with brilliant colouring and long defensive spiny fins.

Cuttlefish

Cuttlefish are not fish but molluscs. They have ten arms and a head bigger than their body. They can quickly change color to camouflage into their surroundings.

Flounder

Flounder is a group of flatfish species that are demersal fish, found at the bottom of oceans around the world. They are known for their distinctive body shape and swimming style.

Giant clam

Giant clams are the world’s largest living marine bivalve and can live 100 years or more. They stay permanently attached to one spot for life.

Great white shark

Despite being a fearsome predator, the great white shark (Carcharodon carcharias) is a threatened species.

Grey nurse shark

The grey nurse shark is a large, stout-bodied shark that can grow up to 3.6 meters in length and weigh up to 230 kilograms. It has a unique pattern of spots and stripes on its body which helps it blend into the ocean floor.

Hammerhead sharks

Hammerhead sharks are known for their unusual and distinctive structure of their heads, which are flattened and laterally extended into a “hammer” shape called a cephalofoil.

Hermit crabs

Hermit crabs are fascinating creatures that have adapted to occupy empty scavenged mollusk shells to protect their fragile exoskeletons.

Leafy sea dragon

The leafy sea dragon (Phycodurus eques) is one of three species of sea dragon found only in Australian waters and nowhere else in the world.

Mantis shrimp

Mantis shrimps are colorful marine crustaceans that have forelimbs modified to spear or stun their prey.

Moray eels

Moray eels are fascinating creatures with elongated bodies and sharp teeth. They have a second set of jaws called pharyngeal jaws that extend into their throat to help them swallow prey.

Nudibranch (Sea Slug) - Photo Jim / Adobe

Nudibranches (sea slugs)

Nudibranchs are a family of opistobranchs (sea slugs) within the phylum Mollusca (molluscs). They are found throughout the world’s oceans, but are most abundant in shallow, tropical waters. Their scientific name, Nudibranchia, means naked gills.

Oystercatcher - Photo John Sandoy / Adobe

Oystercatchers

Oystercatchers are a group of waders found on coasts worldwide. They have black upper parts and white underparts. There are 11 species of oystercatchers in the world.

Potato Cod

Potato cod is a giant fish that can weigh up to 100 kg and grow up to 2 meters long. They are found in the Indo-Pacific region and are known for their friendly nature with divers.

Red-tailed tropicbird

The red-tailed tropicbird is a seabird with almost all-white plumage, a black mask and a red bill. It also has long red tail-streamers.

Clownfish swimming among anemone - Photo papzi / Adobe

Sea anemones

Sea anemones are a group of predatory marine invertebrates of the order Actiniaria. They are named after the Anemone, a terrestrial flowering plant because of their colourful appearance.

Sea stars

Sea stars are marine invertebrates that have five arms surrounding an indistinct central disk. They feed by extending their stomach out through their mouth and digesting prey. They can live up to 35 years.

Sea urchins

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Seagrasses

Seagrasses are marine plants that grow in shallow waters and form meadows in estuaries and shallow coastal waters with sandy or muddy bottoms.

Seaweeds

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Healthy sea sponge on coral reef - Photo the Ocean Agency / Adobe

Sponges

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Western Australian seahorse

The West Australian Seahorse is a large species that is endemic to Western Australian waters. They vary in color and grow to about 22 cm in length. They feed on minute crustaceans and plankton that drift by.