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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 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.

Do you have another great question? Email us at info@beachchairscientist.com and let us know.

Filed Under: Bony Fishes Tagged With: , ,

What are the tiny colorful clams you find under the sand when digging?

July 23, 2008 by 8 Comments

These tiny colorful clams are commonly known as coquina clams.

Did you see them wriggle under the sand? They use a muscled foot to dig a burrow and hide from their enemies: crabs, sea stars, and snails. They can feed themselves with the muscle coming out of the other end, called a siphon. The siphon basically just sucks in the “vitamins” of the sea for the clam to grow on.

Clams grow very fast in the summer and fairly slow in the winter. You can tell the age of a clam by counting the darker rings. The softer rings are the slow growth of winter. Think how your hair grows longer and faster in the summer.

Did you know that colorful coquina clams are the sign of a healthy beach? Check the video posted here!

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

Filed Under: Bivalves Tagged With: , , , , ,

What are jellyfish?

July 21, 2008 by 3 Comments

It was another great weekend on the beach for my family and everyone had new and exciting Beach Chair Scientist questions. The best part about being a Beach Chair Scientist is clarifying misconceptions, so I am going to start with the question that seemed to garner the most discussion this weekend “What are jellyfish?”.

Jellyfish, contrary to their popular common name, are not fish at all! As a matter of fact, neither are starfish. Popular nicknames to avoid this misconception can be to call them jellies or seastars.

Jellies are basically giant plankton. Plankton is anything (living) that is free-floating. It can be a plant (known as phytoplankton) or an animal (known as zooplankton). Jellies are zooplankton. Floating is easy for them. They are over 90% percent water. People are approximately 70% water.  Jellies are in the family Cnidaria (the c is silent). Also in this group are sea anemones and coral.

What do jellies, sea anemones, and coral all have in common?

1. One giant cavity for all digestion
2. Stinging cells (known as nemotacysts)
3. Tentacles
4. Radial symmetry (no matter how you slice it, you will have 2 halves)

Jellies are essentially a giant mouth with intestines surrounded by a skeleton. They have a nerve-net surrounding their transparent skeleton. The nerve-net in some species extends towards the tentacles. Not all jellies have painful toxins in their tentacles.

What do you do if you are infected with a toxin tentacle?

1. Wash with soap and water
2. Apply alcohol, or meat tenderizer and Vaseline
3. Apply ice and contact a doctor

Image (c) pdphoto.org

Do you have another great question? Email info@beachchairscientist.com and just let me know. I can also be reached at Flurl as usual of course.

Filed Under: Jellyfish or Jellies Tagged With: , , , ,