Shark Week – part 1

July 31, 2011

This week I will be joining the SeaMonster blog in honoring sharks and working to build for them a legacy of respect and honor their importance to Panthalassa. http://theseamonster.net/2011/07/shark-week-on-seamonster/

 

Nostril, tooth and eye

Lorenzini Ampullae

Arsenal of sharks

Sharks are masters of perception in the deep. Their keen sense of smell is well known, many figures are available on how many drops of blood can be sensed in how many swimming pool equivalent bodies of water, as is their eyesight, particularly for a fish. I am always most fascinated however with the Ampullae of Lorenzini. This network of receptors on their skin, which concentrates on the head, is able to pick up on the weak electrical fields emitted by nerves and muscles as an animal swims through the water. Because seawater is salty it is able to transmit these electrical signals to the shark. It’s an interesting thing to ponder how this particular sense would feel like to experience. Imagine seeing the movement of an animal, not by sight or sound, but by sensing the very motion of its muscles and nerves.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Orca

July 28, 2011

The pod emerges

White-flecked chatter flanks a school

Death makes room for life

Orcas (Orcinus orca, a.k.a killer whales) are one of the most recognizable organisms in the sea. This is probably due to their success in the animal entertainment world since their intelligence makes them prime candidates as show animals. As with many whales, Orcas are highly social animals that travel and hunt in pods. Being mammals, they dedicate much more time to parental care then most other marine animals. The Orca is a sophisticated and deadly hunting machine. They are apex predators. Until the modern age of man there was nothing in the sea that could hunt down an orca. While this may create an image of savage animals that destroy “helpless” organisms it’s important to understand that top predators are enormously important to ecosystems.  Without them, organisms lower down in the food chain would proliferate and the subtle mechanics of energy transfer breaks down.


Pistol Shrimp

July 26, 2011

Snap! The sound of death

Sonic shock wave in the sea

Light born of bubbles

It’s amazing that an animal as small as a pistol shrimp can, with only its claw, wreak tremendous devistation.  The “pistol” claw, which can be almost as large as the body, has a locking mechanism that allows large muscles to build up tension, thus increasing the power of the claw when it finally snaps shut. The result is a pulse of force powerful enough to create a small cavitation bubble, a small vacuole of empty space in the water, which exists momentarily. Upon collapsing, the bubble can release enough energy to stun or kill prey up to the size of small fish. When this energy is released light is emitted through the effects of sonoluminescence that, though invisible to the naked eye, approaches the spectrum of light from the sun. This efficient hunting method multiplied over the entire population of pistol shrimp makes this group of arthropods contenders as the loudest animals in the ocean.


Caulerpa taxifolia

July 24, 2011

Single-celled seaweed

Clear warm water, a new home

Bottom drowned in green

Caulerpa taxifolia is a green seaweed that is a  champion of the salt water aquarium trade, being able to process high concentrations of animal waste products into benign compounds. It survives well under less than idea conditions that might be found in an aquarium. Because of this it has also been able to become established as one of the worst invasive species in the world. Since an accidental release by a public aquarium in the 80’s, Caulerpa has taken over vast patches of the Mediterranean sea. Caulerpa is protected by toxic terpenoid compounds that can be tolerated by very few marine herbivores. What happens when an eradication attempt breaks up the seaweed? Each piece that is torn off can itself grow into a new seaweed, making clean up attempts extremely tricky.

Caulerpa  are the worlds largest single-celled organisms and are amongst the largest cells of all organisms. A Caulerpa cell can top off at a meter in length. Compare that to a single human skin cell which is .00003 meters long.


Tides

July 20, 2011

Blue-tinged planet spins

Ocean rise, again to fall

’till the end of all

Regular beachgoers tend to develop an innate idea of what the regular rising and falling of the water level means, lost picnics and towels and a confused sense that something is not where it should be. Organisms that live in the intertidal zone, where they are repeatedly submerged in water only to be exposed to air during the next high tide, have mastered a most extreme environment. Half of their life is spend in a rich soup of plankton and other goodies to eat and for the other half half they are exposed to the drying power of the sun and intense heat or cold. They are subject to immense changes in water conditions as freshwater from land mixes with the saltwater of the ocean. Salinty can go from almost freshwater to saltier than the ocean and temperatures fluctuate widely. It’s a life of instability and fierce competition.

These are also areas that can be most effected by human activity and our desire to see the beauty of the ocean and live a life of modern comforts. Much damage has and continues to be done by altering the intertidal habitats to conform with human needs. Sea walls, jetties, quays, dredge spoil, human traffic, hardscaping, roads, housing developing, light pollution, introduced species, wastes disposal…. the list of threats to these valuable habitats is continuously growing. Considering the challenges intertidal organisms face in their natural environment, how long can they survive the addition of human influence?


Mangroves

July 17, 2011

Gulp air, snorkel roots.

Mud will choke you, salt will burn

Life clings in tangles

Mangrove trees (genus Rhizophora) have taken to a very harsh environment, the intertidal zone. It’s hard for any organism, particularly those who evolved back from land to sea, to survive the dessicating effect of salt water. Couple that with the anoxic mud and unstable water conditions of the tropical coastline and you can appreciate why so few plant species can survive. Mangroves are fundamental in creating high biodiversity and sheltering habitat which allows many tropical regions to thrive. Their prop roots provide shelter and physical dimension to what would otherwise be a mudflat, creating nursery habitat, sheltered areas, support for epiphytes, protecting nearby land from erosion and storm damage and so on. Sadly, mangroves are increasingly threatened worldwide. Habitat destruction for property development and for shrimp farming (most shrimp in the US is important from horrendously unsustainable “farms”) threatens thousands of animals and plants that keep the water clean and the shoreline from eroding away.


Endangered

July 14, 2011

Six-Hundred Twenty

Doomed. Too soon to be too few

Lost in the hunger

By January 2010, 620 marine organisms had been listed in the IUCN as being extinct, near extinction, endangered or threatened. This is just an estimate, too many animals are unknown to science to assess the status of all organisms. Ecosystems  will change, adapt to the loss of the organisms and changes in geochemical cycles. The question is whether such ecosystems will support human life. Do what you can now, tomorrow is too late!