Dive Profile
- Tank nº1
- Aluminium, 12L
- AIR mix
- Pressure: start: 210bar
end: 50bar
- SAC: 1.76 bar/min
- RMV: 21.12 L/min
Data provided by EOL.org
Species Identified
Tursiops aduncus (Ehrenberg, 1833) (Indian Ocean bottlenose dolphin)
Megaptera novaeangliae (Borowski, 1781) (Humpback whale)
Humpbacks are baleen whales; they have large, sieve like plates of baleen hanging down from the inside of their mouths which function to filter planktonic organisms from the water . Individuals can open their mouths widel...
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Humpbacks are baleen whales; they have large, sieve like plates of baleen hanging down from the inside of their mouths which function to filter planktonic organisms from the water . Individuals can open their mouths widely, due to the throat grooves, and thus engulf large quantities of water . Humpbacks often lunge into a shoal of prey but have also been observed herding their prey into clusters or using a 'bubble net' to effectively trap greater numbers. During this process, a number of whales will circle underwater emitting a continuous stream of air which traps fish in the centre of the ring, the whales then surface up through their 'net' gorging on the contents within . During the summer months, humpbacks must feed intensely as they do not feed again during either the migration or the time spent in tropical breeding grounds . Males compete for females directly by escorting receptive mates and aggressively defending them, their famous 'song' is also thought to be a form of courtship . Solitary males sing highly complex songs that are similar within a population but evolve over successive seasons . Calves are born after a 10 to 12 month gestation period, they accompany their mother on the return migration to polar feeding grounds, and studies have shown that individuals return to the same feeding ground consistently year after year . Possibly one of the best-known aspects of humpback whale behaviour is their acrobatic aerial display; the most spectacular of which is breaching, when the body of the whale may completely leave the water, returning with an enormous splash .
Chelonia mydas Linnaeus 1758 (Green Turtle)
Green turtles are long-lived and may take up to 59 years to reach sexual maturity Undertaking tremendous feats of navigation, adults return to the same beach to breed each season, part of the population in Brazil astonish...
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Green turtles are long-lived and may take up to 59 years to reach sexual maturity Undertaking tremendous feats of navigation, adults return to the same beach to breed each season, part of the population in Brazil astonishingly migrates around 2,250 kilometres across the open ocean to breed on the Ascension Islands . Mating tends to occur just offshore of the nesting beaches; using a curved claw on each front flipper and a flat nail at the end of the tail, males are able to grip their mates . Females haul out onto the beach at night and dig large nests with their back flippers beyond the high tide mark, they typically lay between 100 and 150 eggs in one nest and then proceed to cover the eggs with sand; the whole process takes around two hours . A single female returns to breed only once every two to five years but will lay up to nine nests in that one season . Incubation takes between 45 and 70 days, and temperature has been shown to determine of the sex of hatchlings; with females being produced at warmer temperatures . Breaking open their eggs with a special hooked 'egg tooth' that will subsequently be lost; hatchlings use their powerful front flippers to reach the surface, and then proceed to the sea . The soft-bodied juveniles are particularly vulnerable at this time from a variety of predators, such as ghost crabs and gulls on the beach to sharks and dolphins in the water . Unlike other marine turtles, adult green turtles are almost exclusively herbivorous, grazing on seagrasses and algae ; it is assumed that juveniles are more omnivorous although the exact composition of their diet is unknown
Manta birostris (Walbaum, 1792) (Giant manta)
Manta rays are generally solitary, although loose aggregations of individuals may occur where there are abundant food sources or during the breeding season. When ready to mate, a male will bite his mate's pectoral fin to p...
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Manta rays are generally solitary, although loose aggregations of individuals may occur where there are abundant food sources or during the breeding season. When ready to mate, a male will bite his mate's pectoral fin to position himself belly-belly for copulation . The developing eggs remain inside the female's body for possibly as long as 12 months and hatch internally so that she gives birth to live young . The average litter size is two pups, and there is often a two year gap between births . These rays feed on planktonic organisms by filtering volumes of water through their mouths. Individuals have been observed swimming in slow vertical loops whilst feeding, possibly in an effort to concentrate prey items . The fleshy projections on either side of the mouth are also used to funnel prey; when not feeding, these lobes are either furled or closed in front of the mouth . Mantas are often host to remoras (Remorina spp.), which attach to the underside of the larger fish and consume particles of food that fall from the mouth . Exceptionally graceful swimmers, manta rays appear to fly through the water on their large wings. Individuals have also been observed to jump (or 'breach') clear out of the water, possibly in a form of communication or play .
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Bart
Australia
Date: 2002-11-04 - 11:05
Max Depth: 14m Duration: 47mins
Dived with
Exmouth Diving Centre
