Saturday, July 02, 2011

Happiness Is a Heterocercal Caudal Fin

I didn't count how many species of fish and other sea creatures came aboard yesterday while fishing with my friend Denny, but I think it was at least a dozen ... if you count the clump of oysters I hooked.

It was a great day for spotting sea turtles, young ones mostly ... hubcap size to trash can lid size. They seemed to be everywhere. We move a lot when we fish, only staying in one spot as long as the fish are cooperating. Each time we zipped off to some new hole or bump in the bottom, sea turtles showed up.

Near the end of our day, as I tried to trick a REDACTED INFORMATION   (top secret by order of the Captain)  fish into taking a small pinfish bait, I hooked this young blacktip shark.

Blacktips are very common around here. Around Cedar Key, you catch them anywhere from cute little foot-long pups to scary, bite your arm off adults, usually while fishing for some other species.

I love getting to see a shark up close, so I never see them as a nuisance. The one below was about 3 feet long..

Captain Denny was busy trying to catch the top secret fish, so I settled for a "hold the camera out with one hand and shoot a self-portrait" technique. I cropped myself out of the shot ... you know how flattering those shots can be.
Feel me?
Fish are the most muscular of all vertebrates and when you hold a shark, even a junior shark like this one, you really get a sense of just how spectacularly "ripped" these beautiful animals are.

I am gripping him very tightly in the picture, partly because he had already flipped loose twice and partly because he is only inches from my cheek (upper right corner of pic) and I value my cheek flesh.

In the photo, you can see where the blacktip name comes from. You can also see tiny specks under his snout that are Ampullae of Lorenzinni. These give the shark a sixth sense ... electroperception.

With Ampullae of Lorenzinni, the blacktip can sense the bioelectric field produced by other living things.
He doesn't have to "see" the crab or ray hidden in the bottom sand. He can sense their nerves firing in the form of a bioelectric energy field.


This young blacktip was released a few seconds after this picture, but not before sideswiping my camera with his caudal fin and sending the Sony crashing to the deck of the boat. At that point the shark went happily into the Gulf and I grabbed the camera to find that it had forgotten what day it was due to the blow.

It also was showing "NO FILES" when I tried to view the days pics.


Any problem with this 6 year old wonderful camera is almost always a button wrongly pushed and not truly a "problem".

Still ... it did just take a heck of a fall ...

It was about then that I noticed the date had reset to 2006 after the blow to it's little Sony brain and of course, there were no photos stored from that year.

I took a deep breath ... I had been holding it since it fell to the deck about 5 minutes earlier ... and reset the date.

A weeks worth of owls, Bear, sea turtles, fish, and birds reappeared.


I did not get to hold EVERY shark we saw of course.

The bonnet head shark below was just cruising around us in the shallow waters near Seahorse Key.

A classically sharky dorsal fin at the surface.

Bonnets are small members of the hammerhead clan. A five footer is a big one. The bonnet's head is flattened and more shovel shaped than the rectangular head of a great hammerhead shark.

Bonnets like the shallows and they love crabs, so it's not uncommon to have one swim by you if you are wading or fishing on the flats.  A flattened head gives you a lot more space for cramming Ampullae of Lorenzinni under your snout.  The better to "sniff" out crabs in the sand.

In this shot, you can see both the flattened head and the very efficient heterocercal caudal fin.
That uneven tail in conjunction with an oily liver and stiff, wing-like pectoral fins,  helps the shark in maintaining buoyancy.

Yes, fish sink.

They have to deal with that through wonderful adaptations. Sharks use the features mentioned above, bony fish use a swim bladder organ that is essentially a gas-filled bag inside their body.

If you dive, just think of your BC vest.

If you don't dive, just think of the swimmee -floatee arm thingies on a toddler in the pool.

The short, short video below is purely accidental. I thought I was taking a still picture, but the camera was still set on video from the day before.

Accident or Sara N. Dippity?



cinbad122 said...

Took the little man to Sea World the other day. Really the only thing he liked was the shark tank and other fish tanks....he could get up close and see all the movement. Although it was after dinner and late for a little man!

Banjo52 said...

As usual, enjoyable and informative, esp. the biz about Ampullae of Lorenzinni. Sure glad I'm not a wader with these guys around . . .

threecollie said...

Sweet! I am so glad your camera is okay. Would have hated to miss your pics.

Lisa at Greenbow said...

I always learn something when I read your blog. May the force be with you always.

tai haku said...

Not sure how but I've never seen a wild bonnethead (and I think I'm due one). Very jealous FC, very jealous.

Anonymous said...

Great post FC! Can't wait for time we can bring our grandson down to show him there's more to Florida than Disney!

Deb said...

Ampullae of Lorenzini- I'm sure that was the answer to a question on a test I took a long time ago.
I'll have to show this post to Joe (Mr. Attitude), who is into all things fish these days.

Miz S said...

Ampullae of Lorenzini? How come no one ever told me about this before? That is AWESOME!

Aunty Belle said...

gick--ok, now, like the gators, snakes, uh huh--the shark too--Mah idea of respect is we leave 'em alone so they woan see us an think it's dinner time.

Glad camera was OK--what a handy tool that camera has been.

Wonderful outing ya had, FC!

ImagineMel said...

FINALLY! A dangerous animal you and I both like!! ;)Glad the camera is A-OK.

Floridacracker said...

That boy has good taste.

I am so used to seeing the bonnets when I wade, that I don't give them a second thought. Their bigger cousins are a different story.


Thanks! That's usually my goal, although, sometimes it's just nonsense here :)

Really? I am amazed. Well, when you do, I'm sure you will get a spectacular UW shot of it!

Looking forward to it!

Fish on!

Miz S,
Welcome to Chondrichthyes, class of awesomeness!

I just stay away from the pointy end myself.
You and me both on the camera. I was pretty worried for a moment there.

It had to happen eventually.

Suwannee Refugee said...

I caught a black tip off of Cat Island last weekend. Thanks for confirming that's what I caught. I was using live finger mullet.

robin andrea said...

I love seeing you have fun with sharks. They are so often maligned. They can't help that they are hungry, have very big teeth, and all those rippling muscles.

kathy a. said...

pretty cute litte shark you were visiting with. great film of the swimming action of the bigger one.

Floridacracker said...

EVERYBODY with a tail loves live finger mullet! Good bait choice.

Well said. This one felt like one single quivering muscle.

Kathy A,
Seeing the cuteness in a shark is a sign of a warm heart.

Dani said...

And sharks to my list of things Dani finds cute.

Floridacracker said...

That list is huge! LOL!

Dani said...

Yes, yes it is. ;)

Took some pictures of a big black widow yesterday. She didn't make my cute list.

Robert V. Sobczak said...

My kids are already better at navigating the camera than I can.