Why are there holes through some clam shells?

November 7, 2008 by 7 Comments

moonsnailholezd2The shell to the right with a hole through it was hinged to another shell of equal size with an animal living inside (e.g., clam or oyster). Animals with two shells hinged together are known as bivalves. Often, in restaurants oysters and clams are shucked and served “on-the-half-shell” (Yum! I prefer them plain, but sometimes mix it up with ones with plenty of horseradish!).

However, animals in the ocean do not shuck their prey, but rather use an adaptation call a radula. A radula is the sharp, drill-like tongue of some mollusks. Radulas are found on every class of mollusk except for bivalves. A whelk or a conch would use their radula to drill into the clam and then slurp out its meal … Leaving behind a perfectly symmetrical hole. Moon snails and oyster drills are also well-known for using this technique to drill into clams for a feast.

Image (c) imageshack.us

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What are those tiny black pods with tendrils near the ends?

October 24, 2008 by 5 Comments

They are egg cases from a juvenile thorny skate. skateThe skate is related to sharks and rays. Sharks, skates, and rays all have a skeleton made up of cartilage, the flexible material that is found in our noses and ears. One tiny skate will hatch from each egg after nine months – hatching under the surface of the water. Usually, what we see wrapped up in the seaweed “wrack line” is the discarded egg cases. Another nickname for these egg cases is the “mermaid’s purse.” Check out this BCS post to learn the difference between skates and rays.

Image (c) NOAA – Alaska Fisheries Science Center.

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Can you tell how old a fish is by looking at it?

October 20, 2008 by Leave a Comment

fishscaleagerings1There is one main way to tell old a fish is while the fish is still alive. And, at that, – it’s still fairly invasive. You need to take some of its scales (see image right).

The scales are similar to the rings of a tree. Depending on how many dark rings you may see, if you were to hold the scale up to a light source, will determine the age of the fish. However, since scales can regenerate often, the rings could be cloudy and difficult to decipher.  You can get a more accurate age of a fish by other methods which require the fish to be dead. These include reading the rings on the cross section of a fish ear bone (otoliths) or fin ray.

Knowing the age of a fish is very important for understanding how to maintain populations and stocks for fisheries management.

Image (c) eralabs.com.

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What lives in the spooky burrows on the beach?

October 19, 2008 by Leave a Comment

The answer is appropriate for this time of year … those quarter-sized holes are the home the ghost crabs or fiddler crabs. I’ll provide some more information for a conversation appropriate for this time of year. Ghost crabs emerge to scavenger upon anything they can get crabs or clams, bugs or insects, plants or dead stuff (detritus). The burrows are personal territories (i.e., not colonies like on Meerkat Manor). If one male tries to challenge another for his home what in sues is an interesting ritualistic “dance.” There is rarely actually contact. So, basically, they better “dancer” wins. If you’re tanning on a beach blanket and hear rapping or bubbling noises under the sand, that’s the ghost crab either using their claws for digging or sounds from their gills as they breath. The burrows can be up to three feet deep.

Top – Ghost crab burrow image (c) aquaessence.com, bottom – fiddler crab burrow image (c) jeb.biologists.org

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Are spider crabs harmful?

October 19, 2008 by 3 Comments

Great question as Halloween approaches!

Common spider crabs, or sometimes called mud crabs, are harmless. In fact, their shells are covered with fine short hairs. When you (if you) attempt to pick one up they would actually feel as though their body was covered in felt.

The short little hairs are really what helps the spider crab survive. They help attach pieces of seaweed or other algae species, sponges or barnacles which aid in its main defense mechanism: camouflage.

These common spider crabs are found along the Atlantic coast from Nova Scotia to the Gulf of Mexico.

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What are the nubby little things on pilings near the beach?

September 30, 2008 by Leave a Comment

Most likely, acorn barnacles.


Let me guess, they look like tiny volcanoes? And they hurt if you rub up against them?barnacles1
That is the outer shell made of calcium. They put this protective layer up when they are not under water.
When it is hide tide the acorn barnacle opens up the volcanoes structure and extends tiny little legs (cirri) all about to gather food circulating in the ocean water.
If you have digested this correctly, you now know the acorn barnacle finds a suitable spot once it is “an adult” and stays there for THE REST OF THEIR LIFE. gulp.

Image (c) uksafari.com.

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Are laughing gulls really funny?

September 20, 2008 by Leave a Comment

NO! Not at all.

Laughing gulls, or Larus atricilla, are quite aggressive. These birds travel up and down the coasts seagulland never have to stray far inland. They are extremely confident and spend their days foraging food from overly-relaxed beach goers. They will easily push larger birds, for instance, a pelican, right out of the way in order to grab the goodies.

These birds do have a black cap of feathers, but, it changes to white in the off breeding season.

Image (c) FreeFoto.com.

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Why is the ocean blue?

September 17, 2008 by Leave a Comment

blueMy immediate answer is that the ocean had a rough day at the office.

A lot of people think it is because of the reflection of the sky, but, that is missing an important part of the puzzle. If you think about it the ocean is not really blue everywhere, is it?

What needs to be said is that sunlight particles may be reflected by the surface of the water, but, some may not. The sun contains all colors of the rainbow: red, orange, yellow, green, blue, and violet. Yellow and red are absorbed immediately within the surface of the water leaving the green and blue to our naked eye.

What does this have to do with the fact that the ocean isn’t blue everywhere? Well, that all depends on what is in the oceans too. Different things absorb the sunlight differently. If the ocean floor is bare, the ocean appears crystalline blue. If there is a lot of plant life (phytoplankton, other plants or organic materials) it will generally appear greener.

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

Image (c) of FreeFoto.com.

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More reasons why I love the Atlantic Horseshoe Crab…

September 11, 2008 by 3 Comments

As I mentioned before, the horseshoe crab is a rather frightening looking creature, however quite the opposite is true, they are the steadfast, strong member of the ocean community. This animal, not only is a vital part of the Atlantic coast food chain, but has remained rather unchanged since before the time of the dinosaurs!

An animal that has been in existence since before the dinosaurs is quite impressive and the main reason I have gotten my 4 year old nephew to learn and love saying the scientific name for the Atlantic Horseshoe Crab, Limulus polyphemus. The “polly-femus” part always cracks him up.

But, seriously, they have remained relatively unchanged and evolved little in 260 million years!

How have they managed this impressive feat?

First of all, it is very difficult for predators to get overturn their tough curved shell and get into the crux of their underbelly!

Secondly, they can go a year without food!

Lastly, they are adaptable and can endure the harshest conditions (temperature and ocean salt levels)!

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

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What eats sea urchins?

September 10, 2008 by 7 Comments
Sea Urchin (Diadematidae) (20 cm)

Image by CybersamX via Flickr

The spines of the sea urchins are there for protection but that doesn’t stop the sea urchin from having enemies. 

For instance, sea gulls love to grab them at low tide at pick away at them high upon the rocks. Crabs have a feast with the urchins by picking away at their spine to get to the inside flesh. Also, urchins that are found along the ocean floor are preyed upon by rays, sharks, seals, and even otters.

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

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