Turtles

Wavelength Reef Charters  can take you snorkeling to the Great Barrier Reef and usually encounter different species of turtles on a daily basis.

Six of the seven species of sea turtles in the world are found on the Great Barrier Reef from Port Douglas:  the Green turtle, the Leatherback turtle, the Hawksbill turtle, the giant Loggerhead turtle, the Flat back turtle and Olive Ridley turtle.

Sea turtles lay their eggs in sand usually on coral or sand cay's throughout the Great Barrier Reef. The temperature of the sand determines the sex of the young turtles. Cooler sand temperatures produce male turtles, while warmer sand temperatures produce females.

Sea turtles can lay up to 100 eggs at a time.

Sea turtles become sexually mature at 30-50 years and can live for up to 100 years.

Turtle hatchlings are carried out to sea on ocean currents, and can travel thousands of miles around the ocean before they are fully grown. When turtles reach breeding age, they return to the same area on the Great Barrier Reef where they hatched to lay their own eggs.

The Leatherback is the largest sea turtle. The heaviest Leatherback turtle ever measured weighed 916kg.

Dolphins and Whales

Whales and Dolphins are marine animals. They live in oceans around the world and a great number of these occur in the Great Barrier Reef Marine Park. Whales and Dolphins come from the same family, CETACEA . Both whales and dolphins breathe from a blowhole located at the top of their head. Whales and dolphins are also mammals, -they are warm blooded and nurse their young from mammary glands.

The Great Barrier Reef is home to some 30 plus species of whale and dolphin including the following;

Hump back whale, Minke whale, Antarctic Minke whale,

Pygmy Bryde’s Whale, Sei Whale, Fin Whale,  Sperm Whale, Pygmy sperm Whale, Dwarf sperm Whale, at least 4 beaked Whale species, rough-toothed Dolphin, Bottlenose Dolphin, Pan tropical spotted Dolphin,  Spinner Dolphin, Striped Dolphin, Common Dolphins, Fraser’s Dolphin,  Risso's Dolphin, Irrawaddy Dolphin,  Melon-headed Whale, Pygmy killer Whale, False killer Whale, Orca,  Long-finned pilot Whale,  and the Short-finned pilot Whale.

Dolphins and Whales have voices, but it's a lot different from most other mammals. The limited visibility under water makes sounds and hearing very important for them. The sounds of the whales are not produced with their mouth/beak but only inside their blow-hole. Whales  also use frequencies that reach far beyond our hearing capabilities.

Whales use sound to communicate. Large whales can communicate over very large distances (several hundred kilometers!) using very low frequencies. Dolphins usually use higher frequencies which limits the distance.

Toothed whales use sound not only to communicate, but also to "see". Similar to bats they send out sounds and listen to the echo that comes back from objects (like fish or rocks). This kind of SONAR (SOund NAvigation Ranging) works very well. Even in complete darkness they can find their way through the ocean and also find their food.

When you listen to the sounds you will usually hear two kinds of sounds. One that sounds like whistling (high pitched sounds) and one that sounds like a rattle or clicking. In general the whistles are for communication and the clicks are for SONAR and echolocation.

All whales and dolphins are protected within the Great Barrier Reef Marine Park.

Clownfish

Clownfish belong to a group of small, brightly colored fish called damselfish and many species of clownfish are found all over the Great Barrier Reef.

There are 27 known Clownfish species. In the wild, all Clown fish species will live among the tentacles of an anemone. The Clownfish manages to avoid being injured by the dangerous anemone because it is coated with a protective slime. The Clownfish has a symbiotic, or mutually beneficial, relationship with the sea anemone. It catches most of its food by co-operating with its host anemone. The Clownfish will leave the safety of the anemone's tentacles and swim out among the nearby reef. Its brilliant colors attract larger fish, who, lured by the thought of a meal, follow it back to the anemone and are stung by the anemone tentacles. The anemone then consumes the fish, and the clownfish feeds on the remains.

In addition to other fish, the Clownfish also feeds on planktonic crustaceans and algae that live in or grow on the Great Barrier Reef. The Clownfish also eats away debris and nibbles off the dead tentacles of its host anemone-a bit like a live in housekeeper!

Many snorkellers perceive the Clownfish as cute and “friendly” as it is much more active and less shy than many other fish species. The truth is however that the Clownfish is more interested in protecting its territory than entertaining snorkellers on the Great Barrier Reef! The Clownfish is a highly territorial fish and it will defend its anemone violently if necessary. Damselfish are renowned for displaying territorial behaviour.

All Clownfish are born male. Clownfish live in small groups with a well established hierarchy. The largest male will be at the top of the hierarchy and eventually morph into a female. The second largest male will form a couple with her and they will breed. The rest of the males exist in sexual limbo, as they can not fertilize the eggs, since their reproductive system is inactive. If the female is killed or otherwise removed from the group, the largest male will turn into a female and the largest of the non-breeding males will become a breeding male. If the male is killed or otherwise removed from the group, the second-largest male will simply take his place and his reproductive system will become activated.

Maori Wrasse

Humphead Maori Wrasse are one of the largest reef fish in the world and are commonly seen on the Great Barrier Reef. They have thick fleshy lips and a large hump that forms on the head above the eyes. Another common name for them is  the Hump headed Maori Wrasse.  The hump of the Maori Wrasse gets larger with age. The cheeks display a fine pattern of cream, wavy lines, bordered above by a distinctive black or brown line that is horizontal behind the eye and slants down to the upper jaw. The markings around the face are reminiscent of New Zealand Traditional Maori facial tattoos, hence the name.

Maori wrasse are very often a territorial  species and sometimes have a ‘home’ cavern, crevice or lagoon in the reef area.  

Humphead Maori wrasse mainly eat during the day and can be seen feasting on shellfish, fish, starfish, sea urchins and crabs. The bones near the throat (pharyngeal bones) act as a second set of teeth that crush, grind and assist in the food processing. They crush large chunks of dead coral rubble with stumpy little teeth to feed on the burrowing mussels and worms. They also feed on large shellfish such as tritons, crushing the shells to get at the animal within. Maori wrasse have also been known to eat small Crown of Thorns Starfish.

Usually they live by themselves but are sometimes seen in pairs. At spawning time a large number of Maori Wrasse can be seen together. Wrasse are ‘protogynous hermaphrodites’ which means they start their adult life as females and change to become males when they are older.

Humphead maori wrasse are very wary of other animals in the wild, but in marine parks where fish are protected they often become quite  tame – like “Killer”…

"Killer" is a resident of Opal reef at a WAVELENGTH Site called “Turtle Bay.” As soon as Killer hears the Wavelength motor he appears at the back of the boat, hoping for a snack of some squid. Killer will hang around the boat at Turtle Bay, rolling his eyes up at our snorkellers and keeping a lookout for more tasty treats. He is happy to interact with our snorkellers and is definitely our FAVOURITE MARINE CREATURE