Blog Archives

Pyura chilensis

Tunicates, commonly called sea squirts, are a group of marine animals that spend most of their lives attached to docks, rocks or the undersides of boats. To most people they look like small, colored blobs. It often comes as a surprise to learn that they are actually more closely related to vertebrates like ourselves than to most other invertebrate animals. Tunicates are part of the phylum Urochordata, closely related to the phylum Chordata that includes all vertebrates.

Because of these close ties, many scientists are working hard to learn about their biochemistry, their developmental biology, and their genetic relationship to other invertebrate and vertebrate animals. A tunicate is built like a barrel...

Identifying sharks in the wild is a great challenge! While scientists can spend weeks examining every detail of a species, divers may encounter a shark for only a few seconds or minutes. Many species look alike and one individual may not be identical to the next. There are, however, relatively few species in any one specific dive site and with some preparation and a little practice it is possible for all of us to recognise the more common and distinctive species.

The key to successful shark identification underwater is a process of elimination, based on a mental checklist of the main features to look for in every animal encountered. One feature alone is rarely enough for a positive identification, so gather as much information as you can before drawing firm conclusions.

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Pseudopercis semifasciata

Canchito is the Uruguayan name for this indicator, the Brazilian counterpart being Namorado. It is also known as the Brazilian Sandperch, and locally as “salmon de mar” or Sea Salmon. Commercially fished off the Southwestern Atlantic coasts, it can be found from Rio de Janeiro in Brazil, to at least the New Gulf in Argentina.

With a maximum length of 120cm, but more typically 50-80cm and weighing 12-18kg, this important indicator has a pale brown body, with darker brown blotches giving rise to dark brown vertical and horizontal stripes. A row of dark brown blotches appears on the middle of the dorsal fin, with a prominent black spot on the upper lobe of the caudal (tail) fin. It feeds on fish, cephalopods, benthic (bottom dwelling) organisms and plants.

Identifying sharks in the wild is a great challenge! While scientists can spend weeks examining every detail of a species, divers may encounter a shark for only a few seconds or minutes. Many species look alike and one individual may not be identical to the next.

There are, however, relatively few species in any one specific dive site and with some preparation and a little practice it is possible for all of us to recognise the more common and distinctive species. The key to successful shark identification underwater is a process of elimination, based on a mental checklist of the main features to look for in every animal encountered. One feature alone is rarely enough for a positive identification, so gather as much information as you can before drawing firm conclusions.

earthdive wants you...

Marsa Alam is a great location for both learners and experienced divers, with a range of trips from shallow wrecks and bays to overnight Elphinstone. Learn to dive or take your diving further with our friendly, experienced team of guides.

Emperor Divers offers the most convenient service available in the Marsa Alam area. We operate dive centres in the Concorde Moreen Beach, Resta Reef and Resta Grand Hotels and our fleet of day boats are moored right on the jetty of the Marina Lodge hotel in Port Ghalib.

The table below shows the diving type, the location, the hotel and transfer times between each. Of course, you can stay at other hotels in the resort and we’ll provide you with a free transfer at set times.

Click here for transfer details.

Volunteer divers can now add a new lesson to their diving knowledge.  Many divers are learning how to help restore the ecosystem by cleaning and preparing new coral for planting in the Florida Keys.

Ken Nedimyer has been working to restore the coral underneath the turquoise waters of the Florida Keys for more than a decade and knows first-hand the tremendous amount of work it takes to replenish a fragile part of the world’s oceans.

“We are trying to put Humpty Dumpty back together again,” said Nedimyer, whose Coral Restoration Foundation has planted four coral nurseries off the shores of the Florida Keys. The foundation offers workshops and diving trips for recreational divers.

“We are trying to get people to realize that it was a lot better and it can be brought back again,” Nedimy...

The Caribbean region

A Coast Guard crew found an illegal gill net with hundreds of dead sharks Monday, 4 miles off the Texas coast.

The crew of a Coast Guard Station South Padre Island response boat spotted the gill net approximately 17 miles north of the U.S. – Mexican maritime border. The gill net was 5 miles long and was loaded with 345 dead sharks.

The species of shark seized included 225 black tip, 109 bonnet, and 11 bull sharks.

“Gill nets indiscriminately kill any fish or marine mammal it snares across miles of ocean, often leaving much of the catch spoiled by the time it is hauled in,” according to Cmdr. Daniel Deptula, the response officer for Coast Guard Sector Corpus Christi...

Chillier seas could be keeping basking sharks away from UK waters, marine experts say.

The Marine Conservation Society (MCS) said it has received hardly any reports of sightings so far this year and it may be down to the cooler than average temperature of the sea.

The basking shark’s favourite food, plankton, fails to bloom in colder waters.

The UK is home to several basking shark hotspots including the seas around the Isle of Man, off the west coast of Scotland and around Cornwall.

Jean-Luc Solandt, MCS senior biodiversity officer, said: “Divers are telling us that the water temperature is 10 or 11 degrees centigrade but at this time of the year it should be nearer 13 degrees.

“This means that the plankton, which is the basking shark’s favourite food and the reason they come to our water...

All over the world, coral reefs, the elaborate graceful structures that serve as the infrastructure of tropical sea life, are turning a deathly white, bleached of all life, mortally wounded. When reefs die, the metropolis of teeming life that surrounds them disappears.

Scientists in Europe found that the bleaching process that kills the reefs is even more complex than they thought. While they were at it, they discovered that the relatively new scientific imaging technique they used to observe the dying reefs may have applications for all kinds of other research, including cancer treatment studies. Science sometimes works that way.

Coral formations consist of a thin layer of living coral that sits atop calcium carbonate skeletons of the dead coral...