BLUE RINGED OCTOPUS

The Blue-ringed octopuses are small animals about 50 mm across from arm tip to arm tip. There are three distinct species that live in rocky shore environments from Australia to Japan. They are carnivores preying on small shrimp and crabs.

Probably the most remarkable aspect of the Blue-ringed octopuses is the potent venom. Delivered by biting, the venom is among the most deadly in the world and has resulted in a number of human deaths. No anti-venin is available at this time.

The venom is a mix of chemicals including tetrodotoxin which is present in the poisonous puffer fish and cone shells. Surprisingly, the toxin is not manufactured by the octopus but by bacteria living in its salivary glands. A bite from a Blue-ringed octopus can result in paralysis of the muscles and possibly a stop to breathing. The heart may also stop through lack of oxygen or paralysis.

First aid usually requires CPR and artificial respiration in hospital. Patients generally recover if respiration can be maintained for the first 24 hours. Because of the paralysis, some victims have been conscious of their situation but unable to call for help. Researchers have estimated that Blue-ringed octopuses carry enough venom to kill about 25 people.

The male Blue-ringed octopus is very enthusiastic where mating is concerned and will wrap his arms around the female to the point that he has to be forced to leave. Male octopuses produce small packets of sperm called spermatophores that are placed inside the female’s mantle (rounded body).

Blue-ringed octopus females lay only one clutch of about fifty eggs just once in their lives. Once the eggs are laid she carries them under her arms in front of her mouth. She does not eat for the six months it takes the eggs to hatch. Once the eggs hatch, the female dies. The young Blue-ringed octopuses will reach maturity and be able to mate by the next year.

My thanks to Zubi and the other photographers for these photos.


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CLIMATE CHANGE AT THE BOTTOM OF THE SEA

If you were asked to show one photo that described what most of the world looked like it would be like the one below. The abyssal plain covers about 60% of the Earth’s surface. Found at depths below 2000 metres it is one of the least well known ecosystems on our planet.

Because it is so deep, so cold, and so isolated, scientists believed that climate change would not affect the abyssal plain. The latest research from a team led by Ken Smith of Monterey Bay Aquarium Research shows that this is not the case.

 

The abyssal plain goes through both short term and long term ecological changes not unlike other habitats. Based on 18 years of research they have found that life at their 4,000 and 5,000 metre deep sites was completely dependant on the life at the surface. As phytoplankton and other surface marine life die they become part of a slow ‘rain’ of food from above.

 

The deep sea "Dumbo" octopus

Changes in the surface waters can have huge effects on how much food falls to the bottom. As shallow water lie dies it sinks and may be eaten and re-eaten several times before it reaches the abyss. The trip from surface to seafloor could take months or even years. It is estimated that less than 5% of the surface food reaches the bottom.

Crinoids (related to starfish) 

 

Studies show that small changes at the surface can affect available food at the bottom by a factor of ten. Scientists have been able to track the 1997-98 El Nino event that caused some abyssal animals to virtually disappear while others increased.

The incredible glass squid

According to Smith, "Essentially, deep-sea communities are coupled to surface production. Global change could alter the functioning of these ecosystems and the way carbon is cycled in the ocean."

The scientists suggest that the abyssal plain could best be studied using underwater robots and ocean floor automated instrument stations. The technology is there to establish a world wide abyssal monitoring program. If we don’t move quickly we wont have the base-line information needed to understand global warming in the deep sea.

Viper fish

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The Amazing Amazon River Dolphin

The Amazon River Dolphin, (Inia geoffrensis), is also called Bufeo, Boto, and Pink River Dolphin as well as a number of local names. This wonderful dolphin species is confined to freshwaters of the Orinoco, Amazon, and Araguaia/Tocantins River systems. It never moves into seawater and can not move up-river above rapids and shallow water.

 

It is the largest of the river dolphins weighing up to 180 kg and reaching a length of 2.6 m. Most adults are pink, but some have darker backs or are mostly gray. It is believed that the Boto's pink color comes from fine blood vessels close to the surface of the skin.

Amazon River Dolphins are unique in that their neck vertebrae are not fused into a rigid structure. Instead they can bend their neck at a 90 degree angle to their body, and skillfully hunt food in the flooded forest tree roots. They have 25-30 peg-like front teeth for catching prey, mainly  crustaceans, crabs, turtles, and fish.

The Boto's eyes seem small and ineffective but are actually as large as those of other dolphins but are protected by fleshy pads. When the rivers are running fast and filled with muddy water, the Boto’s echolocation allows it to navigate through the flooded forest.

Females become sexually mature between 1.6 - 1.8 m in length when they are between 6 - 10 years old. Females give birth to a single calf every 4-5 years. Mother and offspring stay very close for 2-3 years and the calves are fed milk for the first year. Males appear to reach sexual maturity at body lengths over 2.0 m.

Mythology surrounds the Amazon River Dolphin. It is thought to be a shape shifter, able to change to a young man and seduce village women into pregnancy. In the morning the Encantado (enchanted one) returns to the river as a dolphin.




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WHAT'S SO AMAZING ABOUT SHARK SKIN?

More than four hundred million years ago (Paleozoic Era), long before the existence of bony fishes and before dinosaurs roamed the land; primitive sharks hunted the ancient seas much as they do today. From the Paleozoic Era until now, thousands of marine species have become extinct because they were unable to cope with the slowly changing sea or competition with other animals.

The huge prehistoric shark Megalodon was the most dangerous fish to have ever lived.

Sharks have changed very little over the last 100-200 million years and are as successful today as they were so far in the past. One of their secrets to success is their amazing skin.

 

Dermal denticles

 Believe it or not, the outgrowths from the skin of sharks that form minute scale-like structures are similar to miniature ‘teeth’. It is believed that teeth in the earliest vertebrates arose from these tiny outgrowths.

Shark scales are formed of dentine (like our teeth) and originate from the dermal layer of the skin (bony fish scales originate from the epidermis). The dermal denticles are so hard and so sharp that people have used sharkskin as sandpaper. Japanese sword smiths used shark skin for the hand-grips of swords, making them less likely to slip.

Most denticles point backward so sliding your hand from head to tail feels smooth; sliding your hand in the opposite direction is rough enough to abrade the skin.

Studies have found that the denticles create tiny vortices (whirlpools) behind them. By keeping the water turbulence small and ‘clinging’ to the shark’s surface, drag is reduced and speed is increased. Swimming through the water also generates noise that can warn prey of an approaching predator: the denticles reduce the noise making the shark a deadlier predator.

Most sharks have skin colored to fade into surroundings. Midwater hunters are dark above and pale below. From above a shark looks like the darkness of deep water; from below its belly blends into the sunlight above. Sharks that hunt from ambush on the bottom can have colorful skin that looks like seaweed.

A Great White shark cruises the cool waters of South Australia.

Fins and Tails

The fins of bony fish are supported by extensions of bone that run out into a very thin skin membrane. In sharks the fins are thick and supported by rays (filaments) similar to the keratin in feathers and hair.

The shark’s pectoral fins (equivalent position to our arms) are fairly rigid and designed to provide lift to keep the front of the shark from sinking while swimming.

 Sharks have very distinctive tails (caudal fins). The design of the tail is related to its swimming speed, the amount of lift it needs, and how it catches its prey. Sharks have heterocercal caudal fins which mean the top and bottom lobes are different in shape. The larger upper lobe produces a small amount of lift along with forward motion keeping the tail up and balancing the lift from the pectoral fins.

Like the rest of the shark’s body, the fins are covered in dermal denticles. They reduce drag and noise and increase biological efficiency. Energy saved in swimming is converted to growth and size means safety even for these master predators.

A Basking Shark is a harmless species that preys on plankton by filtering tons of water through its gills.

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THE GREENLAND SHARK; A COLD WATER GIANT

No other shark lives closer to the North Pole than the Greenland Shark (also called Sleeper Shark). This cold water giant is closely related to the Pacific Sleeper Shark and grows to 6.5-7 metres in length and a weight of over 1000 kg. 

Greenland Sharks live in the North Atlantic near Greenland and Iceland where they range into water as deep as 2000 metres. Greenland Sharks are ovoviviparous which means that the eggs hatch inside the female and live pups are born. Scientists believe that it may live to be about 400 years old.

The Greenland Shark (and Sleeper Shark) has the reputation of being very slow and sluggish when caught. Divers report that Greenland sharks are not threatening and are slow swimmers but we may not know the full story of these huge predators. The native Inuit people have legends of sharks attacking their boats.

Examination of Greenland Shark stomachs shows that at times they can be fast and hungry. Contents include squid, fish, polar bears, reindeer, horses, and other Greenland Sharks. William Sommers reports that he has seen Greenland sharks snatching caribou from the water's edge.

It is reported that Greenland Sharks have a problem with parasites (copepods) that attack their eyes. The parasites cause scars that interfere with the shark’s sight. Sharks have a number of senses that detect prey and good eye-sight may not be critical for this species.

The flesh of the Greenland Shark contains a powerful neurotoxin and is poisonous to eat. They seem to be immune to their own poison and are able to eat each other.

Teeth photo are from Canadian Shark Res. Lab.

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