Precious Argo

How's the old saying go? "If it looks like a duck, swims like a duck, and quacks like a duck, then it's probably a duck."

"Quack?"

Courtesy: Derek Bruff via Flickr

By extension I can imagine this test applies to any animal. Let's pick a random one and try it, shall we? If it looks like a..... Nautilus, swims like a nautilus, and has a shell like a nautilus it must be a nautilus. 

"Oh my God! What did you just call me!?"

Courtesy: Michael Vecchione via TOLWeb.org

Oh yeah I'm sorry, paper nauti..... I mean greater argonaut (Argonauta argo). I totally forgot about you. How about I make the rest of this post about how awesome you, and the other three species in your family, are to make up for it?

"We can live with that. I'll just sit here and make sure you

 don't mess up again"

Courtesy: NOAA Photo Library via Flickr

Okay where to start? Well, how about at the very beginning like my nanny used to say. Disclaimer: My nanny may have just been Julie Andrews movies. Anyway, we've known about argonauts for an incredibly long time. Their delicate, paper-thin, shells have been found painted on artifacts from 4000 years ago! Of course, back then we barely knew anything about these animals because we were mostly finding their old shells washed up on the beach. 

However many of the ancient Greeks were talented naturalists, and they started looking closer at these coiled beauties. Aristotle noticed that the argonauts could climb out of their shells because they aren't attached to them like a true nautilus or any other shelled mollusk. So how did Aristotle think argonauts got their shell? Well he assumed they stole it. For the longest time scientists thought that argonauts couldn't be making their own shells, so they were taking them from an unknown animal and using them as boats. Now this seems a little crazy, but add in the fact that female argonauts have sail-like webs on two of their arms, and you have the perfect animal to send after the golden fleece. 

Hahaha...What is it even...? Hahaha...There's a boat to compare it to..Hahahaha!

Bless you for this: Gerard Van der Leun, via Flickr

Although the theory that argonauts combined Grand Theft Auto and that pirate Assassin's Creed (Hold on I have to go pitch an idea to Microsoft) persisted well into the 1800's, eventually science started to sober up. We later discovered that female argonauts make the shells using glands in their webs that secret calcite. They spread these webs out over the shell and lay down material bit-by-bit like nature's 3D printer. 

 On the left you can see the webs with chromatophores, extended over the shell.

On the right this female has pulled the webs back, exposing her construction.

Courtesy: Michael Vecchione via TOLWeb.org

 If you're an astute reader, you've probably noticed that I've only mentioned female argonauts so far. This follows the history of these animals because for the longest time we had no idea what the males looked like. Why? You might ask, well they're tiny, like really tiny, only 1% the size of a female, and the biggest species' female only gets to 30cm across. Plus the males don't build shells, oh and sometimes they only have seven arms.

See argonauts are octopuses, and they normally have eight arms like any of their relatives. However one of a male octopuses arms is very different from the others. The third arm on his right side is called a hectocotylus (pronounced: heck-toe-cot-oh-luss) and it's used for reproduction. The males of most bottom-dwelling octopuses insert their hectocotylus into the female's gill opening; and sit there for a bit while a packet of sperm passes from inside his body, down the arm, and into the female's oviduct. Argonauts don't have the luxury of that kind of time though. They differ from their cousins by living up in the water column, instead of down on the sand. Living in the open ocean is great way of avoiding competition with your cousins down below, but it also means you have to travel far and quick to find food, mates, and shelter. 

Because the ocean is so big, and argonauts so small, males may not have many chances to find a female. To make sure they mate effectively the male argonaut's hectocotylus actually breaks off inside the female's body cavity, and he swims away. By embedding his sperm delivery system in the female, the male has insured that it's his DNA that fertilizes the eggs. Plus it's a great way to screw with naturalists. This is not a joke, the scientist who first found a hectocotylus buried in a female argonaut thought it was a parasitic worm!

 Plus what the hell do we call this thing, a septopus?

The eighth arm is kept inside that pouch.

Courtesy: Edwald Rubsamen via Wikimedia Commons and Public Domain

Now here's where the functional beauty of the female's shell can accompany its aesthetic beauty. Since she lives up in the water there's very little to attach her eggs to, and good material could be floating hundreds of miles from the female argonaut, so she lays her eggs right inside the shell. Female argonauts handcraft baby strollers to push their kids around in until they hatch. Not only that, but the shape of the shell allows the female to trap air in its top which helps counter-act the weight of her body and the eggs; and keeps her from rising or sinking too fast. 

You can see the eggs hanging out of the lower part of this female's shell.

She's new to this whole arts and crafts thing.

Courtesy: Bernd Hoffman via Wikimedia Commons

So how'd I do argonaut? Did we cover everything that makes you so cool? Be fair, we don't know much about you since you're all so small and you live in oceans around the entire world.

Whoooo! Nice work! Go team Argo! High eights all around!

Courtesy A.E Verrill via Wikimedia Commons and Public Domain

References:

Finn, Julian K., "Taxonomy and Biology of the Argonauts (Cephalopoda: Argonautidae) with Particular Reference to Australian Material", Molluscan Research, 2013, Vol. 33, No. 3, 143-222.

Heeger, T., Piatowski U., & Moller, H., "Predation on Jellyfish by the Cephalopod Argonauta argo", Marine ecology Progress Series, Vol. 88, 293-296, 1992.

Orenstein, Marcie, "Marine Invertebrates of Bermuda: Paper Nautilus (Argonauta argo)", The Cephalopod Page, 

Accessed via: http://www.thecephalopodpage.org/MarineInvertebrateZoology/Argonautaargo.html 

Mangold, K., Vecchione, M., & Young, R., "Argonautidae", Tree of Life Project, 

Accessed via: http://tolweb.org/Argonauta

A Clam for Ken Kesey

"That's a CLAM!?" This reaction to a particular animal is almost guaranteed when people look at them for the first time. Check it out.

Oh man, who just leaves a tie-dye shirt laying around on a coral reef?
Courtesy: Nick Hobgood via Flickr

Okay first off, that looks nothing like what belongs in my chowder. Second, this animal just goes to prove that the 60's got to everyone. So where does counter-culture clam come from and why's it so psychedelic? Editor's Note: This post is greatly improved when accompanied by Strawberry Alarm Clock's: Incense and Peppermints, or your own favorite psychedelic rock song.

Well what you're looking at is a Tridacna (pronounced: Tri-dack-na) clam. They're more commonly called giant clams, but I don't really like that name because not all of them are giant. In fact one species, Tridacna maxima, has the common name "small giant clam"; that's just silly so were gonna stick with their scientific name for this post. Anyway Tridacna don't look much like their relatives, but all the pieces are still there. They have heavy rippled shells like their cousins the cockles, and the part that you see sticking out is their mantle (the body of a mollusk) and their siphons (The channels clams use to feed and breathe). These combined anatomical parts are what make up the "meat" of the clam that we eat.

Plankton filled water flows into the hole on the right, and strained 
water flows out of the tube on the left.
Courtesy edgeplot via Flickr

Tridacna clams live on coral reefs in the tropical Western Pacific. Once they settle out from the plankton they spend their entire lives in that single spot. They don't dig into the ground, but instead let it all hang out. Truly these bivalves (animals with two shells) have gotten the hippy lifestyle down pat.

In fact it turns out that Tridacna's trippy colors and patterns are essential to its survival. The reason Tridacna don't dig into the sand is that they're part of a self sustaining commune. Just like the stony corals around them; these mollusks host symbiotic algae under their skin. In order for the algae to photosynthesize they need to be exposed to the sun. The hinge of the clam's shell is heavier than the opening, so it can tilt face up and spend the daylight hours with its skin spread out in the light. The algae get protection from consumers, and the clam gets nutrients without having to feed. Having a backup way to get your food is especially helpful on coral reefs because the water around them is usually lacking in plankton. Completely clear water is great for snorklers' ability to see, but not so great for filter feeders' ability to eat.

"Come on baby light my zooxanthellae" -Jim Molluskson
Courtesy: Eric Johnson via the NOAA Photo Library

Now as anyone who's forgotten sun screen on a tropical vacation can attest, the sun at the equator is incredibly strong. Solar radiation in the middle of the day is so intense that photosynthesis can actually decrease as the clam's symbiotic algae try to protect themselves from sun burn. But this is a collective man, and the clam does its part to help the algae function efficiently.

The algal cells under the clam's skin are arranged in stacked towers, which is confusing because that means the cells on top shade out those below them. To counter this Tridacna have their own cool cells called iridiocytes (pronounced: ear-id-ee-oh-sites) which bend light in different directions. The iridiocytes reflect yellow and green light (which aren't used by the algae) away from the stacks, and reflect blue and red light (which are useful) towards them. Essentially the iridiocytes screen out the best light for the algae, soften its intensity, and evenly distribute it across the stacks of cells.

The combination of colorful algae and reflected light come together to create the mind expanding visual experience of looking at a Tridacna's skin. Cameras can't really capture how magnificently colored these animals are, so I really encourage you all to take a trip to your local aquarium and see them for yourselves. But here's another picture to tide you over 'til then.

  Couretsy: Nick Hobgood via Flickr

References:

Holt et al., "Photsymbiotic giant clams are transformers of solar flux", Journal of the Royal Society Interface, Oct. 2014, DOI 10.1098/rsif.2014.0678 Accessed via:

http://rsif.royalsocietypublishing.org/content/11/101/20140678 

Soo, Pamela & Todd, Peter A., "The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)", Marine Biology, 2014, DOI 10.1007/s00227-014-2545-0 Accessed via:

http://link.springer.com/article/10.1007/s00227-014-2545-0/fulltext.html

Stubby, Bobtail, Dumplings

Mollusks. Generally they're not a particularly cuddly bunch. For example, most people wouldn't call the inside of an oyster cute.

"D'aaaww who's a good boy?"

Courtesy: Larry Hoffman via Flickr

But there is one group among the mollusks that stands apart. The sepiolidae (pronounced seep-ee-oli-day) are an order of mollusks related to squid, octopus, and cuttlefish. More commonly these animals are called stubby, bobtail, or dumpling squid. None of the stubby squids get much bigger than around ten centimeters (about half the length of an unsharpened pencil), so they're round and small, which makes all of their common names very appropriate. The squid part of the name is a little misleading however because these animals show characteristics consistent with all of their cousins. They spend most of their lives on the bottom, like octopus; they have eight arms and two tentacles, like squid; and they have short rounded mantles, like cuttlefish. 

Who do you think you are? No, seriously I can't figure it out.

A Hummingbird bobtail (Euprymna berryi)

Courtesy: rtonyr via Flickr

Sepiolids are most closely related to cuttlefish which many people guess by the brilliant colors they can produce. Don't let the flashy get up fool you though; stubby squid are some of the best hiders out there. Not only can they change those colors to better match their surroundings, they're also master excavators.

Sepiolids are so cute that they even snuggle up in a blanket to sleep. They dig down by using their siphon (a tube coming from their body that they use to swim and breathe out.) to force water into the bottom and create a little depression. Then they settle down into it and use their arms to wrap themselves in a nice blanket of mud, leaving only their head sticking out.

Makes sense, you've got to wrap a dumpling 

to steam it properly

Courtesy: Nick Hobgood via Flikr

They spend most of the daylight hours tucked in deep water in their sandy beds and come out at night to hunt. Once they're on the prowl they'll often move to shallower water where they're sometimes encountered by lucky divers. 

So if they're this adorable as adults what do their babies look like? Well pretty much exactly like their parents. Dumpling squid have smaller egg clutches than many of their relatives. They lay up to about 50 eggs, which compared to a giant Pacific octopus' max of 100,000 is practically nothing. And unlike many of their relatives' babies, stubby squid don't spend time as a part of the plankton. The young sepiolids break out of their egg cases ready to roll, and walk away to find some food.

The eggs of the Pacific stubby squid (Rossia Pacifica) 

Courtesy: Chris Wilson via Flickr

You'd think that because these animals are so cute and charismatic that we'd know a lot about them. But because they live at the low end of recreational dive limits, are nocturnal, bury themselves, and tend to live on sandy bottoms which divers often ignore, we actually know very little about the lives of these cool little animals.

References:

Rodrigues et al., "Burying Behavior in the Bobtail Squid Sepiola atlantica (Cephalopda: Sepiolidae)", Italian Journal of Zoology, Apr 06, 2010

Anderson, Roland C.,  "Rossia Pacifica, Stubby Squid", The Cephalopod Page,

www.thecephalopodpage.org/Rpacifica.php