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Snorkeling with Sharks and Manta Rays

Snorkeling with Sharks and Manta Rays
We snorkeled with Blacktip Reef Shark (Carcharhinus melanopterus) in Bora Bora. It is easily identified by the prominent black tips on its fins (especially on the first dorsal fin and the caudal fin). Among the most abundant sharks inhabiting the tropical coral reefs of the Indian and Pacific Oceans, this species prefers shallow, inshore waters and its exposed first dorsal fin is a common sight in the region. Most blacktip reef sharks are found over reef ledges and sandy flats, though they have also been known to enter brackish and freshwater environments. This species typically attains a length of 1.6 m (5.2 ft).

Blacktip reef sharks have extremely small home ranges and exhibit strong site fidelity, remaining within same local area for up to several years at a time. They are active predators of small bony fishes, cephalopods, and crustaceans, and have also been known to feed on sea snakes and seabirds. Accounts of the blacktip reef shark’s life history have been variable and sometimes contradictory, in part reflecting geographical differences within the species. Like other members of its family, this shark is viviparous with females giving birth to 2–5 young on a biennial, annual, or possibly biannual cycle. Reports of the gestation period range from 7–9, to 10–11, to possibly 16 months. Mating is preceded by the male following closely behind the female, likely attracted by her chemical signals. Newborn sharks are found further inshore and in shallower water than adults, frequently roaming in large groups over areas flooded by high tide.

Timid and skittish, the blacktip reef shark is difficult to approach and seldom poses a danger to humans unless roused by food. However, people wading through shallow water are at risk of having their legs mistakenly bitten. This shark is used for its meat, fins, and liver oil but is not considered to be a commercially significant species. The International Union for Conservation of Nature (IUCN) has assessed the blacktip reef shark as Near Threatened. Although the species as a whole remains widespread and relatively common, overfishing of this slow-reproducing shark has led to its decline at a number of locales.

http://www.iucn.org/

http://animals.nationalgeographic.com/animals/fish/blacktip-shark/
During that time we also saw a Lemon shark ( Negaprion brevirostris), a shark that belongs to the family Carcharhinidae that can grow 10 feet (3.0 m) long.[1] It is known as the lemon shark because at certain depths, the light interaction with the local seawater can make this shark have a tanned and yellow pitted appearance, much like the surface of a lemon.

The Manta Rays are also plentiful in the area, are used to humans, and swam all around over and under us and feel like velvet. What the giant manta rays do with humans is unique in this world. A totally wild animal, that can be twice the mass of a horse, seeks out and revels in human physical contact. Manta rays are the largest rays and are closely related to sharks. These harmless rays have a short tail and no stinging spine. They are very acrobatic; they can even leap from the water. Remoras (Echeneida) are frequently seen with mantas, staying near the manta’s mouth (even inside the gill cavities). The remoras probably feed on parasites on the manta’s body and eat bits of the manta’s food. These graceful swimmers are up to 29.5 ft (9 m) wide, but average about 22 ft (6.7 m) wide. The largest weigh about 3,000 pounds (1350 kg).

Mantas are dark brown to black on top with paler margins; they are mostly white underneath. Mantas eat microscopic plankton, small fish, and tiny crustaceans. They funnel the food into their mouth while they swim, using two large, flap-like cephalic lobes which extend forward from the eyes. Mantas have no teeth; they sieve their food.

Star Gazing in the Southern Hemisphere

Did you know that you can’t see the North Pole star after you cross the equator, midsouthern latitudes (15-45 degrees south), but the southern sky is brighter, and there are more stars to see!

Among the exciting celestial treasures that await the traveler who ventures deeper south is the Milky Way–well you say I can see it anywhere, but in the Southern sky it is brighter, especially in our summer, their winter. The Magellanic Clouds, though, can only be seen in the southern hemisphere. Never heard of the Magellanic Clouds?–

From the southern hemisphere the brightest galaxy to be seen is the Large Magellanic Cloud, a smaller galaxy than Andromeda (which we can see in the northern hemisphere), but 14 times brighter. With the naked eye the Large Magellanic Cloud looks like a gray patch in the sky, and the Small Magellanic Cloud nearby looks like a smaller gray patch.

In the 16th century , Portuguese explorer Ferdinand Magellan was the first to note the position and appearance of these two patches, remarking on their uniqueness in the heavens. Today we know they are satellite galaxies of our Milky Way, with the Large Magellanic Cloud about 5 percent of the mass of the Milky Way, and the Small Magellanic Cloud 1 percent of the mass of the Milky Way Galaxy.
Reference: Night Watch
A Practical Guide to Viewing the Universe by Terence Dickinson 4 Edition

On a recent trip across the equator I saw the Large Magellanic Cloud, but the most impressive celestial sight to me was my first sighting of the Southern Cross. Maybe it was impressive because I was also able to get pictures of it! Laying on a deck chair on the Sky Deck of a Cruise ship at 4 or 5 am is amazingly wonderful! You say you aren’t a morning person, well neither am I but I still marveled at the beauty of the sky at those hours, and got up without the aid of an alarm clock! I do have a great lady to Thank for opening my eyes to the southern sky; Famous HAL lecturer, Star Lady Donna. Check her out www.stargazing.ca
Another site to check Skyandtelescope.com for interesting articles, Sky at a glance, Interactive Sky Chart, etc. You can also get Sky Calender on Twitter http://twitter.com.skymaps, then buy yourself a Planisphere for your Latitude and go out and look at the stars!

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