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Temp: Surf 26°C Bottom 80°C
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Dive type : Recreational
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Visibility: Excellent
Water: Salt
Specific gear used
- Computer: Oceanic - OCS
- Mask: Aqualung - Look 2
- Weights: 12 kg
Recent Divers in Elphinstone
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Data provided by EOL.org
Species Identified
Sphyrna lewini (Griffith and Smith, 1834) (scalloped hammerhead)
Forming impressively large schools, female scalloped hammerheads gather in the Gulf of California during the day, around underwater mountains known as seamounts, where they perform a wide range of poorly-understood behavio...
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Forming impressively large schools, female scalloped hammerheads gather in the Gulf of California during the day, around underwater mountains known as seamounts, where they perform a wide range of poorly-understood behaviours . These aggregations are thought to be a result of many sharks, particularly younger females, seeking refuge in a safe place near a rich food supply, although many alternative theories have been put forward . Young scalloped hammerheads also tend to live in large schools, whereas adults usually occur singly, in pairs, or in small groups . These sharks feed on fish, cephalopods, lobsters, shrimps, crabs, other sharks, and rays. They are thought to be potentially dangerous to humans although few attacks have been recorded . The teeth of the scalloped hammerhead are best suited to seizing prey that can be swallowed whole, rather than ripping into larger prey. The hammer-shaped head is thought to be a mechanism to spread out the ampullae of Lorenzini – sensory organs that detect electric currents, chemicals in the water, and temperature changes . Larger shark species may attack young scalloped hammerheads, but adults have no natural enemies. Adults visit cleaning stations where fish known as cleaner wrasse remove parasites from their skin and mouths . During the 9 to 10 month gestation, the eggs of the scalloped hammerhead hatch inside the body of the female. After hatching, but before birth, they are nourished by a yolk sac placenta. The female moves to shallow waters during the summer where she will give birth to between 15 and 31 live young .
Cheilinus undulatus Rüppell, 1835 (Humphead wrasse)
Humphead wrasses are extremely long-lived, known to survive for at least 30 years, and taking around five to seven years to reach sexual maturity . Adults are usually solitary, spending the day roaming the reef and returni...
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Humphead wrasses are extremely long-lived, known to survive for at least 30 years, and taking around five to seven years to reach sexual maturity . Adults are usually solitary, spending the day roaming the reef and returning to particular caves or ledges to rest at night . Very little is known about these fish; adult females are able to change sex but the triggers for this development are not known . Pairs spawn together as part of a larger mating group that may consist of over 100 individuals. The planktonic eggs are released into the water and once the larvae have hatched they will settle out on the substrate . Using their tough teeth, these fish are able to consume hard-shelled species such as molluscs, echinoderms and crustaceans . They are one of the few predators of species that destroy coral reefs, such as the infamous crown of thorns starfish (Acanthaster planci) .
Stenella longirostris (Gray, 1828) (spinner dolphin)
Spinner dolphins move about the oceans in schools; groups that vary in size from just a few dolphins to over a thousand. They commonly school with other species such as pantropical spotted dolphins, or small toothed whale...
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Spinner dolphins move about the oceans in schools; groups that vary in size from just a few dolphins to over a thousand. They commonly school with other species such as pantropical spotted dolphins, or small toothed whales . In such schools, spinner dolphins are known to undertake migrations, following prey or warm water currents . In Hawaii, spinner dolphins usually spend their days resting in shallow bays near deep water, and then move offshore at dusk and feed as they move substantial distances along the shore . Pelagic spinner dolphins feed primarily on small mesopelagic fish, squids and shrimps, and dive down to depths of 300 meters to catch their prey . The dwarf spinner dolphin feeds on reef fishes and other benthic organisms Mating in spinner dolphins appears to be promiscuous, and like many small dolphins, true courtship behaviour can be observed, such as mutual caressing between the male and female . The breeding system may vary geographically, with some populations showing a greater degree of polygyny than others . Calves are born every three years, after a gestation period of about ten months . The mother nurses the calf for up to two years , and they form a bond that lasts a lifetime . Females reach sexual maturity between four and seven years, whereas males do not reach maturity until between seven and ten years . The purpose of the energetic spinning behaviour of the spinner dolphin is not known. It has been suggested that the large cloud of bubbles created by the powerful spin and splash landing may act as an echolocation target, to allow a widely dispersed school of dolphins to communicate . Another theory is that the spinning may dislodge hitch-hiking remoras, or the spinning may, at times, simply be play .
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Bor Glavic
Egypt
Date: 2014-10-28 - 10:23
Max Depth: 30m Duration: 33mins
Dive with Mahmoud Ali from Oriental Divers
