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Interesting Plants and Animals Seen on Pelagic Trips

 Portugese Man 'O War

Sargassum

Yellow- fin-tuna

Pyrosome

  

 

Beautiful Portugese Man 'o War Jelly Fish photographed by Jeff Slovin on BBC June 2010 Offshore Pelagic

The Portugese Man 'o War is a species that indicates the pelagic trip has entered the warm Gulf Stream waters on our Continental Shelf Trips. To understand this see the article on this web site.

The Continental Shelf-Edge:  An Oceanographic Primer for Pelagic Birders

Portugese Man 'o War  Physalia physalis ¹

Often called a jelly fish, the Portugese Man 'o War or Blue Bottle is actually a colony of 4 different polyps each dependent upon the whole.

The colony is found in warm water.  It floats at the surface because of the air bladder (sail)  which the colony fills or deflates. It has no means of locomotion and drifts with the currents and winds.  It rolls on its side from time to time to keep the sail wet.  Sometimes they are  washed up on beaches.  It is known for a painful sting which is rarely deadly.

The Tentacles that dangle from the body, can be 60 feet long and contain nematocysts which sting and kill small fish and shrimp.  The food is then dragged to the digestive polyps. 

Other polyps are for reproduction.

Certain fish are immune to the poison and live among the tentacles.  Since the fish gain a benefit without harming the host this is considered a commensal symbiotic relationship.
Sargassum ²

A genus of brown seaweed that contains two species of brown seaweed that are totally pelagic.  These pelagic seaweeds are never attached to the rock of the sea bottom.  They float because of air bladders in the stems.

Several species of brown seaweed regularly grow in shallow water along the New England coast and are commonly called rock weed. Sea storms may detach rock weed and blow it offshore. where it floats looking much like Sargassum weed.

As pelagic birders, we are most interested in the pelagic species that circulate in Atlantic Gulf Stream commonly called the Sargassum Sea.  The appearance of masses of the yellow brown seaweed indicates that the trip has entered a warm core of Gulf Stream water.  (see above).

Baby turtles and small fish swim with the Sargassum Weed for protection.

 

   Need Picture!
Yellow Fin Tuna caught by the crew of the HelenH.  Sorry guy. Do remember that the only way we get out to the continental shelf edge is on fishing boats and it really isn't the party fishing boats that are depleting the fish stocks.  On this trip every participant took home a tuna steak from the captain of the HelenH.
 
Pyrosoma
 

Folks on the August 28, 2010 BBC pelagic to the Continental Shelf Edge woke up Sunday morning to find that some kind person had placed an example of a Pyrosome on the cooler at the back of the boat with a note "This is a Pyrosome".  I looked it up in Wikipedia and found that it is an unusual sighting.

The Pyrosome looked to be made of clear  plastic.

For more information and some pictures:

http://en.wikipedia.org/wiki/Pyrosome

For some nice pictures taken off California

http://www.divebums.com/FishID/Pages/pyrosoma_atlanticum.html

By the way Wikipedia is a free enclyclopedia which accepts donations.  I donate $35 a year to this most worthwhile project.

 

Emmalee Tarry
From Wikipedia, the free encyclopedia

Pyrosomes, or pyrosoma, are free-floating colonial tunicates that live usually in the upper layers of the open ocean in warm seas, although some may be found to great depth. Pyrosomes are cylindrical or conical shaped colonies made up of hundreds to thousands of individuals, known as zooids. Colonies range in size from less than one centimeter to several meters in length.

Each zooid is only a few millimeters in size, but is embedded in a common gelatinous tunic that joins all of the individuals. Each zooid opens both to the inside and outside of the "tube", drawing in ocean water from the outside to its internal filtering mesh called the branchial basket, extracting the microscopic plant cells on which it feeds, and then expelling the filtered water to the inside of the cylinder of the colony. The colony is bumpy on the outside, each bump representing a single zooid, but nearly smooth, though perforated with holes for each zooid, on the inside.

Pyrosomes are planktonic, which means that their movements are largely controlled by currents, tides and waves in the oceans. On a smaller scale, however, each colony can move itself slowly by the process of jet propulsion, created by the coordinated beating of cilia in the branchial baskets of all the zooids, which also create feeding currents.

Pyrosomes are brightly bioluminescent, flashing a pale blue-green light that can be seen for many tens of meters. The name Pyrosoma comes from the Greek (pyro = "fire", soma = "body"). Pyrosomes are closely related to salps, and are sometimes called "fire salps." Sailors on the ocean are occasionally treated to calms seas containing many pyrosomes, all bioluminescencing on a dark night.

 

References

1. Wikipedia    http://en.wikipedia.org/wiki/Portuguese_Man_o%27_War

2. Wikipedia   http://en.wikipedia.org/wiki/Sargassum_weed

3. Wikipedia  http://en.wikipedia.org/wiki/Pyrosome

Last updated: 09/01/2010