Showing posts with label dolphins. Show all posts
Showing posts with label dolphins. Show all posts

Saturday, 28 June 2014

DOLPHINS IN THE MILITARY







Man’s best friend may be the dog but today, a sailor’s best friend is a marine mammal. I know; this is a very controversial subject but let's just look at some facts.

Sea lions and dolphins served in the military during the first Iraqi war. The animals were used to detect mine fields that were placed to blow up American ships. Contrary to some reports, the marine mammals are treated very well. They are given the best food and their trainers are with them night and day. They are too expensive and too important to be treated badly.


Because these animals work in open water without the supervision of the trainer the marine mammal will only return to the ship if it wants to. Training is based on a bond of trust between the marine mammal and the trainer. The work has to be fun and mentally stimulating as well or the marine mammals lose interest. remember, they are intelligent animals and get bored with routine.




This dolphin is carrying a camera on its flipper and signaling that it has finished its photo mission. The sea lion is fitting a recovery line to lost equipment.






The Navy doesn’t take any chances with injuring their ‘divers’ because training is too expensive and replacements can take years to train.

Sea lions have the advantage over dolphins in being able to climb into boats and helicopters; dolphins have to be transported in large tanks of water or follow their trainer’s speed boats.




Civilians have been working with sea lions for search and rescue in open water. Some research facilities now take their dolphins into the ocean for exercise. They return to their pens when they have had enough and want to spend time with their trainers.

Dr. Ted explained, “This kind of work with marine mammals requires a lot of careful interaction with the animals. They have to trust us as much or more than they trust a member of their own species. Working as partners with marine mammals is probably the best part of my job.”







Wednesday, 9 April 2014

MEGALODON THE SUPER PREDATOR














Megalodon is a Greek name given to a now extinct giant shark that roamed the world’s oceans between about 2 and 25 million years ago. Megalodon literally means “big tooth”. It is the fossilized teeth that tell us much about what we now know was a ‘super predator’; the king of the oceans.


 


The teeth were so large that early finds were once believed to be petrified tongues of the dragons. 

Estimates vary, but we are confident that Megalodon grew to about 15 metres in length and quite possibly to 30 metres and was the largest shark ever to exist.


 
 Megalodon (gray and red) with the whale shark (violet), great white shark (green), and a human (black) for scale. Note: The maximum size attained by megalodon is indicated by the 20 m scale. Wikipedia


Scientists are certain that Megalodon preyed on whales, dolphins, and possibly giant sea turtles. Whale bones (including vertebrae and flippers) have been found with clear signs of large bite marks made by teeth that match those of Megalodon. Additionally, some geological excavations have found the giant teeth with the chewed remains of ancient whales.

 




In 2008 Dr. Stephen Wroe conducted experiments to determine the bite force of Megalodon. He found that very large specimens were capable of exerting a bite force of up to 275 Mpa (40,000 pounds per square inch); over 5 times greater than that of T. rex). 

Megalodon was probably the most powerful predator to have lived on Earth.





Most sharks are opportunistic; they will feed on a wide range of species and even scavenge for food. Some large sharks (including the great white shark which is a distant relative of Megalodon) attack their prey with great force. 

Their strategy is to inflict as much damage as possible and then follow their prey until it dies from blood loss. This not only saves energy but avoids the risk of injury in a fight to the death.



Scientists believe that Megalodon was no different than today’s big sharks. Fossil evidence shows that Megalodon attacked the larger whale’s flippers (with their large blood vessels) and the rib cage. In both instances the prey would have bled to death quickly.



Sharks like Megalodon have ‘sawing’ teeth that can carve out huge chunks of meat from their victims. 



 A reconstructed jaw of Megalodon shows the replacement teeth that would move up to maintain a sharp bite.


Megalodon’s jaws would have opened to a size of 2m wide and 2.3 m high. Its bite could have held as much as 5-6 m3 of flesh or about 6 tonnes of food. 

Thursday, 20 June 2013

DOLPHIN INTELLIGENCE by Dr Gerald Goeden


Dolphins are found throughout most of the world oceans. Here in the Andaman Sea we are lucky enough to have 9 cetaceans:
  • Indo-Pacific finless porpoise (Neophocaena phocaenoides)
  • Indo-Pacific humpback dolphin (Sousa chinensis). Also known as the Pink Dolphin or White Dolphin.
  • Irrawaddy dolphin (Orcaella brevirostris)
  • Indo-Pacific bottlenose dolphin (Tursiops aduncus)
  • Long-beaked common dolphin (Delphinus capensis c.f. tropicalis)
  • Gray’s spinner dolphin (Stenella longirostris)
  • Pantropical spotted dolphin (Stenella attenuata)
  • Bryde’s whale (Balaenoptera edeni)
  • Dugong (Dugong dugon)
There are many times that dolphins have rescued swimmers or fought off attacking sharks at real risk to themselves. Because of these actions, humans tend to feel there is a special bond between dolphins and themselves and that this bond is based on mutual intelligence or a wished for understanding.

From as early as the 17th century scientists have been impressed by the size of dolphin brains and rated them near the top of the ‘non-human’ intelligence list. Many cetaceans (whales) do have large brains and, relative to body size, toothed whales have larger brains than baleen whales. In fact, the relative brain size of bottle nose dolphins is nearly the same as that of humans. Dolphin brains range from about 0.25% to 1.5% of their body weight and human brains are about 1.9% of our body weight.


Another measure of brain development is based on the number of folds in the grey matter (cerebral cortex). This is the part of the brain that gives us conscious control of our bodies and thoughts. Toothed whale brains have more folding than baleen whales but much of this is taken up for sound production and processing. Toothed whale brains, like the dolphin’s, have folding that resembles that of hoofed animals like horses and deer.

We don’t know if dolphins have a language but we do know that they share information about their surroundings, their emotions, and their identity through acoustic whistles and clicks.


Memory experiments with dolphins showed that their picture of the world and their ability to remember it was better when based on their sonar and not so good when based on sight. Their memory was best when they could use sonar and sight together.

Dolphins have also been taught ‘words’(using hand signals) that can be put together in two-word sentences like “get ball”. Scientists found that they understood these sentences about 80% of the time. Able to grasp the basics of human language, it may be possible to communicate in two and three word format with dolphins in the future. If we do decide to talk with dolphins it will be best to choose our subjects wisely since research shows a large variation in ‘intelligence’ among species.

We think of intelligence as the ability to understand our surroundings and process information so that we can react in the most favorable way. In this way intelligence is not the same as instinct where reactions are ‘pre-programmed’ in the brain. In the animal kingdom, species with higher intelligence tend to be social animals that live in groups.

It is thought that the evolution of intelligence is related to the need to understand group dynamics and the individual’s place within them. The ‘smarter’ dolphins operate in social structures similar to dogs and primates.



Having a well developed brain and intellect; humans are always quick to make lists showing the relative intelligence of other animals with us at the top. To be fair, we must always ask the question: “How intelligent would we be in the dolphin’s world of sound and social behavior; in a world without landmarks and signs; and without shelter and an organized food supply?”