Cephalopodcast

Parchment tube from Chaetopterus mixed with thousands of dead urchins, © Jason Robertshaw

What the Shell Is That? is my semi-irregular series on beachcombing and tidal life. Living on the west coast of Florida, it is mostly about shells, but can also be about other flotsam, fauna and even flora.

Parchment Tube Worms (Chaetopterus sp.)

Date: 12 March 2008
Location: Siesta Key, Sarasota, Florida, U.S.A.
All along the wrack line.

Kingdom: Animalia
Phylum: Annelida
Class: Polychaeta
Order: Spionida
Family: Chaetopteridae

Parchment Tube Worm (Chaetopterus sp.)

Report:
We had some storms roll through recently that managed to dislodge quite a number of benthic invertebrates. All kinds of critters were washed up on the beach, some in the thousands. There were worms, sea urchins, sea shells and seaweeds of all different kinds and colors. It was good pickings for the beachcombers but even better pickings for the shore birds.

One of the castoffs that piled up in the wrack line were the casings from parchment tube worm (Chaetopterus veriopedatus). Normally these worms burrow into the sand with either end of the tube poking out (see illustration here). The worm itself has several highly modified, bell-like paddles that they beat inside the tube to maintain water circulation. One of the neatest aquarium exhibits I’ve seen was a live Chaetopterus placed inside some clear vinyl tubing. It was thereby possible to watch the rhythmic beating of its paddles. Here’s a photo of a similar set-up.

Another critter that my wife found was one that has long been on my life-list but is so obscure I did not recognize it at the time (hence the poor picture). It was a Polyonyx sp., or a commensal porcelain crab that lives almost exclusively in the tubes of parchment worms. It is rare to find them anywhere else and this one presumably was dislodged from one of the many casings on the beach. You might note how it’s claw seems oddly bent. It wasn’t broken but appeared to be shaped that way.

There were also casings from another type of worm called the decorator or plumed worm (family Onuphidae). You may have heard about the recent debunking of bug eyespots as being mimicry. Well there is a similar amazing story underwater with these creatures. Recent research from Sarah K. Berke and Sarah A. Woodin (University of South Carolina) suggests that the Onuphid’s tube decoration may not be for camouflage after all.

References

• Ruppert, Edward and Richard Fox. Seashore Animals of the Southeast. Columbia: University of South Carolina Press, 1988. 203.
• Williams, Winston. Florida’s Fabulous Seashells. City: World Publications (Tampa, FL), 1988. pp. 39
• Witherington, E., Blair and Dawn Witherington. Florida’s Living Beaches. City: Pineapple Press (FL), 2007. pp. 125.

Additional Links

• Woods Hole Marine Biological Laboratory: Chaetopterus variopedatus (Tube Worm). Includes nice pics of the worm and Polyonyx.
• Polychaet Diverstiy and Feeding: Chaetopterus
• Science Musings: Red fish, blue fish…
• Google Docs: A Study of the Life History and Habits of Chaetopterus Variopedatus, By Howard Edward Enders (Published 1906)
• Biological Bulletin Online: Tube Decoration May Not Be Cryptic for Diopatra cuprea (Polychaeta: Onuphidae) Berke and Woodin Biol Bull.2008; 214: 50-56
• National Geographic: Hawai’i’s Unearthly Worms
• ScienceDaily: Zoologists Challenge Longstanding Theory That ‘Eyespots’ Mimic The Eyes Of Predators’ Enemies

Eggcase from a skate. © J. Robertshaw

The Great Eggcase Hunt

With the coming of spring in the northern hemisphere also comes a time to hunt for eggs. But it’s not just about birds anymore. The folks over at the Shark Trust also want people to head to the beach to look out for the fecundity of fish.

Colloquially known as mermaid’s purses, eggcases are the protective capsules laid by skates and some rays**. Inside is a tiny baby skate and a big yolk sac. Typically the capsules have odd keels and horns to help them remain tangled in seaweed and camouflaged on the bottom. The young develop for several months before hatching out as miniature adults. But after hatching, the horny cases begin to breakdown and may come loose, washing up on the shore. Storms might also dislodge living ones from the bottom. If you find a lot of eggcases in an area, it may indicate that a skate nursery is located nearby. This kind of information is valuable to conservationist who are trying to protect these species.

Why does the Shark Trust want you to record eggcases? In recent decades several species of skate and ray around the…coast have dramatically declined in numbers…The identification of these critical areas will enable the Shark Trust to propose conservation measures, in order to reverse the decline of these charismatic animals.

So now’s your chance to contribute to skate and ray conservation and have a lot of fun at the same time.

They have a lot of resources for citizen scientists and for educators who want to organize a local eggcase hunt. And if you don’t live near the coast, you can still take some time this spring to create your own giant eggcases (PDF link) out of balloons and papier-mâché. Or better yet, make some chocolate ones that you can send to me!

• Great Eggcase Hunt
• A Fieldguide to Eggcases (PDF)
• **What’s the difference between a skate and a ray?

Rabbitfish Helping to Save the Reef

Continuing with my aquatic version of things vernal, there is news that rabbitfish might be helping to save the Great Barrier Reef. Many herbivorous reef fish species like parrotfish and tangs regularly graze on the fast-growing algae of the reefs. But apparently they only like to eat it when it’s young and not too weedy. This is where the rabbitfish comes in.

“Then, to our even greater surprise a fish we had never seen in this area before was observed grazing on the weed. The rabbitfish (Siganus canaliculatus), came out of nowhere and began to clear-fell the weed placed on the reef crest.”

The rabbitfish were caught on underwater videocams, in schools of up to 15 fish, grazing the crest, slopes and outer flats of the reef, and chomping away at more than ten times the rate of other weed-eaters.

• Red Orbit: Rabbitfish Helping to Save the Great Barrier Reef
• Science Daily: Rabbit Fish To The Rescue Of The Reef

sƎʇɐʞs ɹƎɥ :ɐ*

I have not gone out to the beach as much as I had hoped when I first started What the Shell. But not too far from the horse conch, we found this little fellow.

Stone Crab (Menippe sp.)

The one pictured below is probably a juvenile M. mercenaria, the Florida Stone Crab. That’s based on the range; I haven’t found anything definitive yet.

2 September 2007
New Pass, Sarasota, Florida, U.S.A.
Found crawling on a dead quahog shell.

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Superfamily: Xanthoidea
Family: Menippidae
Stone Crab (Menippe sp.)

Gortoning Myself

I am probably Gortoning myself with this one, but stone crab season begins today in Florida.

Only legal-sized claws (2 ¾ inches) are harvested in the stone crab fishery; crabs are returned to the water alive to generate new claws. Approximately 13 percent of commercially harvested claws are regenerated. The fishing season is open October 15 through May 15 each year, but the harvest of egg-bearing female crabs is prohibited at all times.

Most of the sources on stone crabs note that this is a “sustainable fishery,” owing to the notion that the crabs will regrow their claws. The rate of regrowth varies, taking anywhere from one to three molts before the new claw approaches the same size as the one removed. The molting rate depends on the initial size, sex and environmental conditions of the animal, among other things.

Duress of the Dungeness*

You can file this under duh, but Mark recently noted some new research that indicates crabs with claws removed have increased stress levels which could affect survival rate. As picked up by ScienceDaily:

Professor Bob Elwood, from the School of Biological Sciences studied crabs’ reaction to declawing. Crabs felt increased stress and had a lower survival rate after the removal of one claw.

Professor Elwood said: “We found a strong stress response within ten minutes of taking off one claw and this stress remained after 24 hours. The stress response was greater if the crab was declawed rather than being induced to cast off a claw. So, the stress is not due specifically to claw loss but to the manner of the claw loss.

I don’t imagine most folks will pay much mind to this news. But personally, I’ve cut back tremendously on the amount of meat I consume, mostly for ethical and environmental reasons. And this research doesn’t incline me make an exception for crustaceans, no matter how deliciously sustainable they may be.

Sources

• Blogfish: Removing claws is harmful to crabs
• ScienceDaily: Declawing Crabs May Lead To Their Death, which is a rehash of the original press release from Queen’s University, Belfast.
• NOAA FishWatch fact sheet: Gulf and Florida Stone Crabs (Menippe adina and Menippe mercenaria)
• The 2006 Stock Assessment Update for the Stone Crab, Menippe spp., Fishery in Florida
• A Proposed Evolutionary History of Stone Crabs
• Observations of the Stone Crab Commercial Fishery. From the 2006 season, with a couple of nice vignettes by Florida Wildlife Commission field crew members.
• Creative Loafing, Sarasota: ‘Tis the Season, Sandy claws are coming to town. Brian works in an jab at vegetarians in both the print and podcast versions.

*Forgive me the poetic license, I know they are different species. This also concludes my Blog Action Day report.

Last Sunday was International Rock-Flipping Day. I made another 60 second video highlighting some of our discoveries. It’s a little choppier production, since I only had the Powershot A95 (movie setting). Once again, edited with iMovie and scored in Garageband.

Click To Play

Blip.tv | YouTube

• Official IRFD declaration
• Flickr: International Rock-Flipping Day photo pool
• Previously: International Rock-Flipping Day is September 2

I am starting another new feature here on the Cephaloblog, one that I hope will become a regular edition. I am calling it, What the Shell is That?

My inspiration comes from the weekly blog arcs of folks like PZ Myers (Friday Cephalopod), Peter and Craig (Friday Deep-Sea Picture), Rick MacPherson (Monday Moray) and Martin Brummell (Friday Fish), to name just a few.

The focus of What the Shell will be on things I find at the beach. Living on the southwest coast of Florida, that means mostly molluscs, especially bivalve (clam) and gastropod (snail) shells. But it could also be skate eggs, algae or nurdles. Anything in the intertidal is fair game, and not just dead things on the beach either.

Note, I am not a professional malacologist or a competent conchologist. Just a curious beachcomber looking to get outside more to search the surf and share with you. I am not interested in collecting live shells, just taking pictures and leaving only footprints/bubbles. I hope to post one entry each weekend, the day depending on when I can hit the beach.

Florida Horse Conch (Triplofusus gigantea)

The official state shell of Florida is neither a horse (obviously) nor a true conch (not so obviously) nor is it limited to just Florida. True conchs are in the family Strombidae, but horse conchs, along with the tulip shells, are in the spindle shell family Fasciolariidae. Up until recently this particular animal was known as Pleuroploca gigantea. I am still not certain what prompted the change in taxonomy.

I suspect it is called a horse conch because it is the largest snail in North America. These animals grow up to two feet long and are voracious predators of other marine snails.

The individual pictured above was a juvenile, approximately 3 inches long (7.5 cm) found half-way in the water on a piece of drift wood.

Some questions I am still seeking the answers to:

• Why is the horse conch orange? How does it get this distinctive color.
• As an adult, why does it have such a flakey periostracum?
• Why is the horse conch so large?
• Why the change from Pleuroploca to Triplofusus?

References

• Rehder, Harald and James Carmichael. The Audubon Society Field Guide to North American Seashells. New York: Knopf, 1981. pp. 575.
• Ruppert, Edward and Richard Fox. Seashore Animals of the Southeast. Columbia: University of South Carolina Press, 1988. 116.
• Williams, Winston. Florida’s Fabulous Seashells. City: World Publications (Tampa, FL), 1988. pp. 54-55
• Witherington, E., Blair and Dawn Witherington. Florida’s Living Beaches. City: Pineapple Press (FL), 2007. pp. 73.

Additional Links

• More photos: What The Shell
• Whitney Laboratory of Marine Bioscience: Horse Conch (Pleuroploca gigantea)
• Spindle Shells, Scallops, an excerpt from Florida’s Seashells by Blair & Dawn Witherington (pdf)

UPDATE: bobsonguam now informs me that Pleuroploca papillosa is being considered.

Sticking a tentative tentacle into the world of video podcasting. This first one is something of a test.

60 Second Sunset, Siesta Key, Sarasota, FL

Click To Play

Shot on 07/28/2007 with my peewee Canon ZR500. Edited with iMovie and scored in Garageband. Inspired by this series 60 Seconds in the Life of the Galapagos Islands over at Ironic Sans.

• Cephalopodcast on YouTube
• Cephalopodcast on Revver
• Cephalopodcast on Blip.tv

BTW, my buddy SB just coined a new word tonight. I was asking him about youth culture and the balkanization of all these social networking sites. He said that geeks go to blip.tv and the “general public & yutes go YT [YouTube].” So there you have it:

yutes |yoōts|
noun
1. [informal] plural for young adults.
2. [slang] YouTube enthusiasts (often obsessive youths).

youts
British spelling of yutes