Archive for October 2006

The Ultimate Shark Picture Quest   Leave a comment

A few days ago I was talking to the Editor of Shark Diver Magazine (SDM) about a Small Spotted Catshark Article that I wrote. He was planning to call it simply; Cat Shark. I pointed out that if he did that then he couldn’t run another catshark story for some time and considering that there are 138 different species of catsharks that seemed like a bit of a waste.

The conversation drifted into a discussion about the upcoming Shark Divers TV show which has changed considerably since it was first penned. The original idea was to make a show about shark diving and us getting shark pictures and stories for SDM. That is still the primary focus of the show but we have added an additional challenge; we want to film 100 species of sharks. Why? Well, apart from the fact that it probably hasn’t been done before, it’s another excuse to do what we love doing. I will also be able to add a lot of new species to the Elasmodiver Field Guide to Sharks and Rays.

It would be a lot of fun trying to film that many species for TV. In fact, I would be satisfied just trying to get that many shark pictures for the magazine, but after the catshark argument I sat down and started to think through the idea more clinically. Was it a realistic goal or would it become a show about a couple of guys failing to film 100 shark species? I made a mental tally of the sharks I have seen since I started diving. I believe I am just shy of 50 species. Not bad considering that I didn’t become a professional photographer until a couple of years ago but then again, it’s been getting a lot more difficult to find new animals lately.

Getting new shark pictures has become a challenge that is slowly consuming me and the difficulties are not all related to budget or my limited time in the water. Of the almost 500 species of sharks that are out there, a tremendous number are simply beyond the reach of the average diver. I have the advantage of being a part-time submersible pilot but even in that job I have few opportunities to locate deep water sharks. Not surprisingly, when a large metallic submarine cruises over the seabed with lights blazing in all directions, the sharks of the abyss (with their sensitive opalescent eyes) turn tail and flee at lightning speed. I’m not just talking about deep sea lantern sharks and dogfish. Thumbing through my Collins’ Sharks of the World it appears that nearly all of the ornately patterned catsharks that would look so at home on a shallow coral reef, actually inhabit the twilight zone below 100 meters.

Another nightmare that limits my quest for shark pictures is the phrase ‘prefers turbid water and muddy bays’ Turbid water is caused by wave action churning up the sediment or by rivers dumping huge quantities of silt into the sea. Lots of species of sharks live exclusively in these low visibility environments. Their highly tuned senses are more than adequate for them to navigate through this sightless world but shark photography is virtually impossible.

So, unless we intend to catch all these elusive sharks and relocate them to places where they are easier to film (you’d be surprised how many shark pictures are staged) we are in for some frustrating shark trips. Can it be done? I believe so but even if we fall short of our target we have lost nothing and gained one hell of an adventure. I guess I’ve always been on this mission anyway so publicizing it on a TV show merely adds some time constraints to a quest that I was expecting to last a lifetime.

For the Sharks,

Andy Murch

Host of Elasmodiver.com – a web based field guide containing shark and ray information and thousands of pictures of sharks and rays.

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Posted October 27, 2006 by Andy Murch in Nature, Photography, Sharks, TV Shows, Uncategorized

Stingray Barbs and the dangers posed by Stingrays   2 comments

Steve Irwin’s sad death has generated hundreds of emails to Elasmodiver requesting information about stingrays and stingray barbs. Rather than try to answer them all individually I have created a page that covers most of the questions that people have been asking:

What do Stingray use their barbs for?
Stingrays use their barbs (also known as tail stings or tail spines) as defensive weapons to protect themselves from sharks and other predators. However, rather than risk potentially dangerous confrontations they generally swim away when approached by divers or other large animals. Using their barbs to attack is definitely a last resort.

Do Stingrays use their barbs when feeding?
They do not use their barbs to kill their food because their diet generally consists of invertebrates that live under the sand or mud. They dig in the sand and suck up their lunch sometimes crushing it between their flat, plate-like rows of teeth.

How exactly does a stingray use its barb?
The Stingray jabs forwards with its tail held over its head like a scorpion. Threat displays have been witnessed in which a stingray held its tail aloft while it was receiving close attention from a shark. Great hammerheads (a major predator of stingrays) have been found with as many as fifty spines lodged in their throats.

What is a stingray’s barb made of?
Stingray skin is covered partially in dermal denticles (literally ‘skin teeth’) that contain dentine just like normal teeth. They look like short pointed spikes when viewed under a microscope. The ray’s tail spines are modified dermal denticles that have become elongated so that the can be used as defensive weapons.

Are stingray barbs poisonous?
The Stingray’s barb is covered in a mildly venomous sheath of skin. When the barb is pushed into a foreign body the venom is released. The venom is a protein-based toxin that causes a lot of pain in the area of the wound and may also alter the heart rate and affect the respiration in a victim.

 

How do you treat a wound from a stingray barb?
The wound should be immersed in the warmest water that the victim can stand. This will immediately start to break down the toxins and alleviate much of the pain. Once the pain has been brought under control the wound should be irrigated to ensure that no fragments from the stingray barb remain. Secondary infection is common and a physician may recommend antibiotics to avoid complications.

 

What happens to the Stingray after it loses its tail spine?
If the stingray loses one of its barbs while defending itself, it immediately begins to grow a new one. Stingrays shed and re-grow their spines on a regular basis regardless of whether they use them.

 

How many spines do stingrays have?
Depending on the species, stingrays may have up to 7 or more spines although most have one or two.

 

What types of rays have tail barbs?
Families of rays that possess tail spines include Whiptail Stingrays, Round Stingrays, River Stingrays, Eagle Rays, Cownose Rays, and Mobula Rays.

 

How common are injuries and deaths from stingray barbs?
Very rare! There are very few records of stingrays killing humans and when these cases do occur the actual cause of death is usually secondary infection not the wound itself. The most common victims are beach and river fishermen and others who spend a lot of time wading in shallow water. Stingrays are greatly feared in the Amazon River where stingray wounds are relatively common and expert medical attention may be difficult to get.

 

How can you avoid being wounded by a stingray?
Again, the chances of a beachgoer being stung are very small but there are a few things that you can do to lessen the chances even further. Stingrays attack when they are pinned down and unable to swim away. If you shuffle your feet instead of taking raised steps you are less likely to trap any stingrays that are lying buried under the sand.

 

Divers should avoid cornering rays (or any dangerous animals) against the reef or swimming directly over them as this could be perceived as a threat.

Stingrays need protecting!
Since the tragic incident with Steve Irwin there have been reports of reprisals against stingrays involving fishermen cutting off their tails and leaving them to die. Not only is this practice barbaric, if it gets out of control it will upset the balance of the environment. Stingrays (like sharks) play an important role in keeping the numbers of invertebrate animals in check. If the rays are wiped out from a particular area the entire localized ecosystem will begin to change. Imagine what a plague of snails could do to a reef if there were no stingrays to keep their numbers down.

Stingrays have a right to defend themselves but they are generally gentle and timid. They are extremely graceful creatures that appear to ‘fly’ through the water like giant birds and the world would be a lesser place without them.

Andy Murch

Host of Elasmodiver.com a web based field guide containing shark and ray information and thousands of pictures of sharks and rays.

 

For more information on Stingrays visit the following pages:

Whiptail Stingray Information

River Stingray Information

Elasmodiver Shark and Ray Field Guide

 

Posted October 3, 2006 by Andy Murch in Environment, Nature, Sharks, Uncategorized