How does an oyster make a pearl?

Chargrilled oysters

Image via Wikipedia

Oysters are another bivalve animal. In the case of all bivalves, the part of the animal that lines the shell is known as the nacre and the part of the animal that make up the outer shell is known as the mantle. A pearl is created rather by accident when something foreign gets stuck inside the mantle, thus the nacre builds up to protect the animal. This build up is known as the pearl.

Oysters, mussels, and clams all make pearls. However, they are most often seen in oysters. My theory is that the oyster shells are typically not as uniform in shape as clams and mussels and tend to grow according to their surroundings, making it easier for foreign junk to accumulate.

Are flounder born flat?

They hatch from the egg looking exactly like typical fish, swimming in the upper waters. After two weeks the bridge of the fish’s nose fades away and then one of the eyes, depending on the species, shifts to one side. The process of becoming a complete “flat” fish takes a bit of time, but, once complete the flounder is content to live the rest of its life on its side on the bottom of the ocean floor.

Winter flounder move their left eye to the right side. Summer flounder move their right eye to the left side. There are many more flounder species, but, this is just an example of where their eyes shift.

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Why are there holes through some clam shells?

moonsnailholezd2The shell to the right with a hole through it was hinged to another shell of equal size with an animal living inside (in this case, a clam). 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!).

Animals in the ocean do not have the luxury of someone shucking their prey, but rather use an adaptation called a radula. A radula is the sharp, drill-like tongue of some mollusks (e.g., whelk or conch). 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

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

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?

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

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) it 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 (otolith) 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?

The answer is appropriate for this time of year … those quarter-sized holes are the home the ghost crabs or fiddler crabs. Ghost crabs emerge to scavenger upon anything they can get including 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 occurs is an interesting ritualistic “dance.” There is rarely actual contact and the better “dancer” wins. If you’re tanning on a beach blanket and hear tapping 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.

ghostCrab

F1.mediumTop – Ghost crab burrow image (c) aquaessence.com, bottom – fiddler crab burrow image (c) jeb.biologists.org

Are spider crabs harmful?

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?

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?

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?

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.