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What allows jellies to float?

March 5, 2009 by Leave a Comment

Jellies don’t technically float; they’re neutrally buoyant (or close to it). Floating would be bad. It would mean being stuck on the surface, like a boat. Jellies are mostly water-up to 96%. What’s left is mostly the “jelly” in a jellyfish, the mesoglea. Jellies sink exceedingly slowly, and make up for it with just a little bit of swimming. A few pulses of the bell can keep them in place, but that’s about it. Jellies can swim all day and not really “go” anywhere. These gelatinous gems are the world’s largest plankton-completely at the mercy of the ocean currents.

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: Jellyfish or Jellies

Is a starfish really a fish?

February 20, 2009 by 1 Comment

No. The classic common name is very misleading. Scientists and environmental educators are transitioning their language to seastar when referring to this animal because, well, it is not a fish.

The seastar is in the same family as the sea urchin, sea cucumber, sand image_sci_animal021dollar and a few others that all have these things in common: fivefold radial symmetry, spiny skin and a water based vascular system.

The family is called the “echinoderms” which means spiny skinned.

Image (c) dk clipart.

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Filed Under: Echinoderms

Why do I always see so many dead crabs along the shoreline?

February 19, 2009 by Leave a Comment

Rest assure those crab skeletons are not all dead crabs. They are the molts from the animals. Crabs, lobsters, horseshoe crabs, and many other crustaceans go through a molting phase and the old shell is basically washed up in the wrack line.

The wrack line is the deposits from the ocean after the tide has gone back out to sea. It’s often defined by seaweed that entangles lots of fun ocean treasures such as sea beans, old leathery sea turtle eggs, and sometimes marine debris. It’s my favorite spot to explore!

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Filed Under: Algae (Seaweeds), Atlantic Horseshoe Crab, Beach Tagged With: , , ,

What’s the difference between a conch and a whelk?

February 17, 2009 by 3 Comments

Good rule of thumb would be that whelks are found in temperate water and conchs are found in more tropical waters. Also, conchs have eyeballs, while whelks have eyespots. If you’re lucky enough to catch them while feasting, whelks are carnivores and conchs are herbivores. Also, their body colors are different. Conchs tend to be green or gray while whelks are tan or whitish (but can be other colors).

Filed Under: Mollusks, Univalves Tagged With:

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.

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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.

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Filed Under: Beach, Seashells, Univalves

How do sea spiders distribute nutrients throughout their bodies?

November 21, 2008 by Leave a Comment

If anyone has ever come upon a sea spider you immediately think – where are its guts and stuff? huge-sea-spiderThe answer is that their stomach, intestines and reproductive parts are housed within the sea spider’s legs. The animal breathes and manages waste by direct diffusion along the surface of it’s bodies. They can be a foot across – but, most types are barely more than 0.05 of an inch across! They do have a global distribution.

Sea spiders are not in the same exact family as other spiders. However, the sea spiders and terrestrial spiders are in a class together…along with one other creature, Horseshoe Crabs! Yup, horseshoe crabs are more directly related to spiders than other types of crabs.

Image (c) sethwhite.org

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Filed Under: Arthropods

Do isopods live in the ocean?

November 19, 2008 by 1 Comment

Yes. There are 45,000 different types of marine isopods. Isopods are crustaceans and have a body divided into three parts: head, thorax and abdomen. Actually, isopods are the most diverse of all the types of crustaceans and are unique because they are the most widely distrubed crustacean out there! When in doubt, call it an isopod…

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Filed Under: Crustaceans

How do sea stars eat?

November 18, 2008 by 4 Comments

StarfishFirst, sea stars grip their prey (e.g., bivalves, such as clams and oysters) with their suction feet and pry them apart to eat the muscle inside the shells. Then, once the bivalve’s shell is open, the stomach of the sea star emerges from the middle of the underside of its star-shaped body to absorb the delicious entrée inside itself. After this happens, the animal is full and not going anywhere soon (e.g., me after Thanksgiving dinner).

A sea star is another common name for starfish. Scientists, and the likes of me, are on a campaign to get people to refer to this echinoderm as the ‘sea star’ instead of a starfish. Since, well, they simply are not fish. Similarly, jellies are not called jellyfish anymore.

Check out this video from the Monterey Bay Aquarium of a sea star chowing down!

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Filed Under: Echinoderms Tagged With: , , , ,

What are those yellow looking things that look like a floppy spinal cord?

November 14, 2008 by 2 Comments

The strand of half dollar sized pods is an egg case. Actually each pod has about twenty tiny animals in each pod.knobbed_whelk_with_egg_-case_100_2886

The tiny animal that will grow from this egg case is the knobbed whelk. This is basically a northeast version of a conch (pronounced conk). If you hold the tiny discs up to the sunlight you can see the tiny versions of the whelk developing.

The whelk is a mollusk (like clams and oysters) but only has one shell. This shell grows with the whelk as it gets older – as opposed to the hermit crab which moves out as it gets bigger.

Also, if you hold the whelk shell up to your ear you can hear the ocean. Lastly, do not hold up a whelk shell to your ear if it has a tough protective “door” covering its opening. That’s the mantle and means that an animal inhabits the shell. Please place it right back where you found it.

Image (c) Jo O’Keefe.

 

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Filed Under: Egg Cases, Mollusks, Univalves