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What do sand sharks eat?

February 17, 2009 by 5 Comments

“Sand shark” can be a bit of a catch-all term, but it seems to most commonly refer to the sand tiger shark, Charcharius taurus. Sand tigers are an interesting case study in form following function in shark teeth. Sand tigers have long, narrow, prong-shaped teeth—like the tines of a fork. Their teeth are perfectly shaped for spearing slippery prey like fish and squid. But while slippery swimmers make up the bulk of their diet, it is worth pointing out that sharks are always opportunistic. Sand tigers are not above snapping up a wayward crab or lobster.

Jim Wharton
Vice President, Education Division, Director, Center for School and Public Programs, Mote Marine Laboratory

Filed Under: Fish, Sharks

What is the rarest shark species?

February 13, 2009 by 2 Comments

There are plenty of candidates. The deep-diving, plankton-feeding megamouth shark was discovered as recently as 1976 and is only known from 40 or so specimens. A group of species called “river sharks” seem pretty rare. Some have been described from just a single collected specimen. There are many deep sea sharks that have only been caught a handful of times. Does that make them rare? Maybe we’re just lousy at finding them?

What is clear is that many species are much rarer than they used to be. One study finds shark populations in the Mediterranean Sea down 97%. Another found oceanic whitetips in the Gulf of Mexico down 99% since the 1950s. Large predators are naturally uncommon as it is. It takes a lot of energy in an ecosystem to support them. It’s up to us to make smart decisions when it comes to seafood and coastal development to keep them from becoming even rarer.

But we’ve only scratched the surface here. Check back often at http://www.beachchairscientist.com for more insight about your favorite beach discoveries.

Jim Wharton
Vice President, Education Division, Director, Center for School and Public Programs, Mote Marine Laboratory

Filed Under: Sharks

What is the difference between a summer and winter flounder?

February 13, 2009 by 2 Comments

I would suggest laying it flat on a surface with the head facing your left hand. A summer flounder will have their eyes swiveled to the top of their heads and their mouth will be under their eyes.  Their mouth will actually also extend behind their eyes. A winter flounder will have their eyes closer to you while their mouth would then be above their eyes. Also, their mouth is considerably smaller and doesn’t go past their eyes.

Flounder are born with a body type in balanced symmetry, in other words , looking like normal fish. As they continue to grow, their bodies morph to the left or right so their eyes and mouth are on one side. Then they rest on the bottom of the ocean floor on the other side.

That explains that flounder are flat fish with their eyes and mouth on one side of their head. Now, whether the eyes and mouth morphed left or right will be the answer to the question.

OK, quite simply if you were to catch a flat fish and think of only these two options (summer or winter flounder) I would suggest laying it flat on a surface with the head to your left a summer flounder will have their eyes swiveled to the top of their heads and their mouth will be under their eyes.  Their mouth will actually also extend behind their eyes. A winter flounder will have their eyes closer to you while their mouth would then be above their eyes. Also, their mouth is considerably smaller and doesn’t go past their eyes.

Please keep in mind that there are Gulf flounder and bunch of others, but we will keep it simple.

Summer flounder are generally darker. But, that type of answer doesn’t help when you have nothing to compare.

what type of flounder is this?

So, test your knowledge and leave a comment to answer this question: What type of flounder is pictured above? (And it is facing right to throw you off base.)

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Filed Under: Bony Fishes Tagged With: , ,

How do sandbars get started?

January 27, 2009 by Leave a Comment

The current closest to the ocean floor is moving offshore and dumps small piles of sand right at the wave break area. The sand accumulates to various degrees, and regardless it makes the water much shallower where you stand. Now, the sandbars that I am thinking of are very long and are parallel to the coastline. But, the same type of accumulation occurs in the open water, these are known as shoals. A sandbar is a type of shoal.

 

Filed Under: Beach, Ocean

Do sharks have bones?

January 2, 2009 by 6 Comments

No sharks do not have bones.

Sharks do have skeletons, but they’re made of cartilage rather than bone. Cartilage is the flexible stuff in the tip of your nose. A cartilage skeleton has its advantages. It’s light, flexible, and it heals faster than bone. In some spots though, sharks need a little extra strength. Their skulls, jaws, and spine are fortified with calcium salts, making them much thicker and stronger. Can you think of why a shark would need strong jaws, skulls, and spines?

by Jim Wharton
Vice President, Education Division, Director, Center for School and Public Programs, Mote Marine Laboratory

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

Filed Under: Sharks, Skates and Rays Tagged With: , , ,

Are stingrays related to sharks?

January 2, 2009 by 7 Comments
English: Various types shown. Taken at Mote Ma...

Image via Wikipedia

Stingrays and sharks are very closely related. They belong to a group of fishes called the elasmobranchs. All elasmobranchs have 1) skeletons made of cartilage (the flexible material that makes up the tip of our nose and ears) and 2) 5-7 gill slits. Elasmobrachs includes sharks, rays, and skates.

It’s not entirely incorrect to think of stingrays as flattened sharks. On the inside, they’re just about the same. There are some animals that blur the lines between the two. Angel sharks and wobbegongs are flat, but they’re not rays. Then there are sawfish (which are rays) and sawsharks (which are sharks). Sharkrays are just plain confused. As a general rule, if the gill slits are on the bottom, it’s a ray. If they’re on the side, it’s a shark.

Jim Wharton
Vice President, Education Division, Director, Center for School and Public Programs, Mote Marine Laboratory

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

Filed Under: Sharks, Skates and Rays Tagged With: , , , ,

How does coral bleaching result?

December 22, 2008 by 1 Comment

Coral bleaching is due to the fact that the algae part of the coral reef ecosystem can no longer photosynthesize properly – therfore, losing the “reef” structure and the corals remain white – since the zooxannthellea are not around (that’s the algae – and responsible for the color of the coral). This occurs due to a lack of sunlight – mostly from a build up of substances (usually, man made – on the surface of the ocean).

Filed Under: Algae (Seaweeds), Coral Reef Ecosystems

What is the second largest reef in the world?

December 22, 2008 by 2 Comments

Interesting question.

The top three largest coral reef ecosystems in the world are:

1) Great Barrier Reef off the coast of Australia

2) Belize Barrier Reef

3) Florida Keys Reef Ecosystem

A coral reef ecosystem relies on teamwork between the coral animal (a type of cnidarians) and an algae called zooxannthellea.

Filed Under: Algae (Seaweeds), Coral Reef Ecosystems

Do lobsters mate for life?

November 25, 2008 by 1 Comment

The male lobster is apparently quite the Casanova. Studies have shown that female lobsters tend to patiently wait in line outside of a male lobster’s den waiting for their turn to mate. One could say lobsters are apparently the ocean’s version of a rock star.

The males really do have all the right moves – for the brief time they do spend together, it is actually rather romantic…

Here is the scenario:

You see all lobsters have to molt (release their shells and grow a new one to be comfortable). Females can only mate right after molting. So, when she is ready to get comfortable in her new shell, the female releases a pheromone (a scent saying she is ready to get comfortable) into the male’s den.

The male then comes outside and the two of them have a boxing match with their claws. The female lets him win and places her claws on his head. Then they move into the den and – in a few hours or a few days – she molts. Then it is time to mate. After that she hangs out until her new shell is strong enough to protect herself – at which point she is ready to go and never looks back.

Do you have another great question? Check out www.beachchairscientist.com and let us know what you always ponder while digging your toes in the sand!

Filed Under: Crustaceans

What makes the swirly tracks at the ocean edge?

November 25, 2008 by Leave a Comment

What I think you are referring to is the trail of a moon snail, or sometimes called a sand snail. This univalve animal has a cinnamon bun swirled shell. The shell is extremely thick to protect itself from the ocean and other animals that may try to eat it.

If you try to pick it up – the animal will resist because of its suction like muscled foot planted in the sand. The snail has that muscled foot which makes it glide quickly through the sand. If you do pick it up and feel resistance – it is ok, the animal will “close its door” – or operculum – and hold in water and nutrients. And, of course, you will put it back right where you found it? Now, it you see some colored legs poking out – that’s a hermit crab. They may pinch – so put it back – quickly. Hermit crabs make their homes out of shells that are no longer homes to other animals…

Lastly, this is type of snail is the one that has the radula which drills into clam shells.

Do you have another great question? Check out www.beachchairscientist.com and let us know what you always ponder while digging your toes in the sand!

Filed Under: Beach, Seashells, Univalves