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Whales don’t have scales

October 10, 2010 by Leave a Comment

That’s right. Whales are covered in blubber because they are mammals like you and I. Now the fish in the sea are another story. You might not realize it, but, if you’ve ever had the opportunity to touch a shark they are covered in scales just like other bony fish. There are several main types of scales that cover fish. See if you can figure out which cover sharks.

1.) Ctenoid scales: These scales are comb-like with the ends having small teeth-like structures.

2.) Ganoid scales: These scales are heavy and diamond-shaped.

3.) Cycloid scales: These are round scales with smooth edges.

4.) Cosmoid scales: These scales are very hard and covered in enamel.

5.) Placoid scales: These scales have teeth-like edges. They are different than ctenoid scales because they lack they rounded front.

Scales grow out of the skin and have modified to quite a few different versions over the years. In fact, the feathers of a bird are a type of evolved scale!

Filed Under: Bony Fishes, Fish, Sharks, Skates and Rays

12 good non-fiction books about fish

September 29, 2010 by 3 Comments
  1. Four Fish: The Future of the Last Wild Food by Paul Greenburg (read a review here.)
  2. Cod: A Biography of the Fish That Changed the World by Mark Kurlansky
  3. On the Run: An Angler’s Journey Down the Striper Coast by David Dibendetto
  4. Giant Bluefin by Douglas Whynott
  5. The Last Fish Tale: The Fate of the Atlantic and Survival in Gloucester, America’s Oldest Fishing Port and Most Original Town by Mark Kurlansky
  6. The Unnatural History of the Sea by Callum Roberts
  7. Tuna: A Love Story by Robert Ellis
  8. The Most Important Fish in the Sea: Menhaden and America: H. Bruce Franklin
  9. The End of the Line: How Overfishing Is Changing the World and What We Eat by Charles Clover
  10. The Empty Ocean by Richard Ellis
  11. 5 Easy Pieces: The Impact of Fisheries on Marine Ecosystems by Daniel Pauly
  12. Striper Wars: An American Fish Story by Dick Russell

Beach Chair Scientist also has list of great movies, fiction books and blogs about the sea!

Image (c) Island Press.

Filed Under: Fish, Random Fun! Tagged With: , , , , , ,

What is bioluminescence?

September 26, 2010 by 1 Comment

Bioluminescence means light (as in ‘illuminate‘) from life (prefix ‘bio‘).

It is produced by a chemical reaction in many marine or terrestrial organisms. The reaction begins with a chemical called luciferase that catalyzes another chemical, luciferin, to then make oxyluciferin and light.

If you see bioluminescence from a boat it is most often tiny dinoflagellates near the surface of the water that begin this chemical reaction once they’re excited. A boat or a passing porpoise can trigger this excitement. On land we are familiar with bioluminescence in fireflies and a glowing fungus, called foxfire.

But, did you know bioluminescence is responsible for illuminating the majority of our habitable world? That’s right, the deep sea is the largest area of habitable space on our planet. A large number of species that utilize this adaptation live in that environment. Here are some images of the inhabitants of the deep sea that use bioluminescence:

Deep sea shrimp, Acanthephyra purpurea

Deep sea fish, Photostomias guernei

Blackdevil angler fish, Melanocetus johnsonii

All images (c) NOAA.

Filed Under: Fish, Places Tagged With: , , , , ,

How do fish give birth?

September 10, 2010 by 7 Comments

There are three general ways fish in the sea give birth to a new generation.

I will start off explaining what is most familiar to us, fish that give birth to live young. This is called being viviparous. There is a structure similar to the placenta that connects the embryo to the mother’s blood supply. Some shark species are viviparous. In fact, in some shark species such as the shortfin mako, the embryo has been known to eat other eggs developed by the mother.

Next is something similar called giving birth oviviparously. This is when the embryo develops inside of an egg that is inside the mother. The difference between this and viviparity is that the embryo gets no nourishment from the mother. Nutrients are taken from within the egg. Coelacanths are a type of oviviparious fish.

Lastly, I will go over how 97% of fish species reproduce. These are the fish that lay many, many eggs and hide them in a dark corner so predators can’t get to them. This is called being oviparous. With most oviparous fish species fertilization takes place outside the body. But with many types of skates and rays (pictured right) the male will use his claspers to internally fertilize the female eggs before she lays them.

Image (c) www.gma.org

Filed Under: Bony Fishes, Egg Cases, Fish, Sharks, Skates and Rays Tagged With: , , ,

Visit to the Smithsonian

September 4, 2010 by Leave a Comment

I am excited to bring you a look into the Smithsonian’s American Museum of Natural History. We are taking a sneak peek into the Department of Ichthyology with Research Curator, Melanie Stiassny. Ichthyology is the study of fishes. In this collection you will see the ceolacanth, Latimeria chalumnae, the three lobed caudal finned fish considered to be the missing link between fish and tetrapods (animals with four limbs).

Filed Under: Fish

Why don’t fish freeze in the Arctic Ocean?

September 3, 2010 by Leave a Comment

Fish species that frequent the cold temperatures of the Arctic Ocean (e.g., toothfish, cod, ice fish, etc.) have special ‘antifreeze’ proteins within their blood stream that enables them not to freeze in the cold waters of the northern hemisphere. This discovery was made about 50 years ago.

Recently, scientists from the Ruhr-University Bochum in Germany discovered how these proteins work. In the presence of the proteins, water molecules in the blood stream act in a more uniform fashion and are more particular about the bonds that they create. Whereas without the antifreeze proteins, water molecules just create haphazard bonds. Now we understand why fish can survive in the temperatures of the polar oceans which are below what should freeze fish blood.

The scientists made this discovery by using a technique called terahertz radiation on an Antarctic toothfish, Dissostichus mawsoni.

Journal reference:
Simon Ebbinghaus, Konrad Meister, Benjamin Born, Arthur L. DeVries, Martin Gruebele, Martina Havenith. Antifreeze Glycoprotein Activity Correlates with Long-Range Protein−Water Dynamics. Journal of the American Chemical Society, 2010; : 100816142208022 DOI: 10.1021/ja1051632

Image (c) wikimedia.com

Filed Under: Fish Tagged With: , , ,

What is a fish kill?

August 23, 2010 by 1 Comment

Like it or not sometimes fish kills occur. It is a harshly worded phrase used to define a massive localized die off of a fish population. When there is a fish kill it is a serious matter that environmental agencies use an indicator something may have run a muck in the local ecosystem. Although, fish kills can occur due to natural causes or artificial causes.

For instance, recently in New Jersey the Department of Environmental Protection (DEP) determined that a menhaden fish kill was attributed to a lack of oxygen (hypoxia). It seems as though over one million of the tiny bait fish were swam right into shallow water, perhaps being chased by a predator such as bluefish. All those fish in the shallow water used up the limited oxygen before the tide could take them back out to sea. The water was tested by the DEP and was said to have a very low oxygen level due to very warm air and water temperatures. Fish kills are very prevalent in the warmer months. Other natural causes of fish kills may include drought or underwater earthquakes.

Meanwhile, in Mississippi there was a similar fate for speckled trout that may have been caused by the tar balls and patties that locals have been seeing wash ashore.  Thermal pollution (heated water let off of a nuclear plant), oil, chemical or hazardous waste spills are some of the major causes of man-made fish kills. The use of oil water separators technology can also help in filtering the oil, chemical or hazardous waste spills.

What can you do to prevent a fish kill? Please do not over fertilize your lawn, overstock fish in your pond at home, feed ducks or sport fish, and always try to prevent garbage from entering your local watershed.

Photo (c) http://ian.umces.edu

Do you have another great question? Email info@beachchairscientist.com.

Filed Under: Fish, People Tagged With: , , , ,

15 facts about sharks

August 4, 2010 by 1 Comment

1.) Sharks are divided into 8 orders.
2.) Sharks are again divided into 34 families.
3.) There are over 360 shark species.
4.) The largest meat eating shark is the great white shark (37 feet).
5.) The largest shark is the whale shark (and largest fish overall), a filter feeder.
6.) The second largest shark (and fish) is also a filter feeder, the basking shark.
7.) Dwarf laternfish (7 1/2 -8 inches), the spined pygmy shark (8 inches) and the pygmy ribbontail catshark (7-7 1/2/ inches) are among the smallest of the sharks.
8.) The fastest swimming fish are the mako and blue sharks which can swim upwards to 60 miles per hour.
9.) The shark with the strongest bite is the dusky shark with a jaw of 132 pounds of force.
10.) The dogfish is the most common shark species.
11.) The deepest diving fish is the Portuguese shark.
12.) The shark with the longest migration has been found to be the blue shark.
13.) Megalodon was an ancient shark that may have been 2 or 3 times as long as a great white shark.
14.) Megalodon means “giant tooth”.
15.) The fossilized teeth of a megalodon are as large as an adult’s hand.

Filed Under: Fish, Sharks Tagged With: , , , , , ,

What to eat this summer?

June 23, 2010 by Leave a Comment

From Good (an on-line web magazine dedicated to enabling  individuals, businesses, and non-profits to push the world forward) an infographic of the popular Monterey Seafood Watch Guides.

Filed Under: Fish, People, Random Fun!

No more fish in the sea

June 17, 2010 by Leave a Comment

From Good (an on-line web magazine dedicated to enabling  individuals, businesses, and non-profits to push the world forward) an infographic detailing the decline of popular fish species in the last 50 years. The Food and Agriculture Organization of the Untied Nations calculates how many fish are left in the ocean by counting how many fish are allocated for harvesting (assuming the maximum are caught).

Filed Under: Bony Fishes, Fish, Ocean Tagged With: , , , ,