January 2004
Being an engineer who studied audio in school as a prelude to being a famous record producer (at least that was the plan), and now with my own recording studio at home, I've always had a strong interest in sounds and how they're made and recorded. Recently I found out something very interesting related to sound about a critter we all know but know so little about.
We're all familiar with the clicks of the dolphins and the low moans of the humpback whales, but do you know what animal makes the loudest noise known on earth?
It's Moby Dick - the sperm whale. The sperm whale, like the dolphin, uses its head to focus sound into a narrow beam, somewhat like a laser focuses light. This animal produces a click lasting only 1/10,000 of a second which can be detected 15 miles away. If heard in the air, its clicks would be louder than a jumbo jet taking off. The energy in such a sound blast could stun fish in the path of the beam.
Using a government scanner originally designed to scan solid fuel rocket motors, a cephalopod researcher named Ted Cranford somehow managed to CT scan the 600 pound head of a small sperm whale (an adult male sperm whale's head can be 25 feet long) to build a 3D picture of its internal structure, and the results were nothing less than astounding.
Prof Cranford's scans illustrated how the whale produces the clicks at the front of its nose, just inside the blowhole, where a gigantic pair of "lips" is located. The clicks then travel backward from the lips through its spermaceti organ, which magnifies and focuses the sounds. The clicks then bounce off the back of its skull, traveling forward through lens-shaped pockets of fat which focus the clicks into an intense beam of sound.
For more 3D photos from his research, including an animated 3D image , the CT scans and a rare view of those "lips", go here. Wanna hear sperm whale clicks?
For more reading, click here.
August 2002
Seeing the Light
As bio-elitist humans, we tend to view the systems of other animals as "primitive" if they aren't as complex as ours. Our brain is the ultimate example of this.
The eye is another example. Many people think that the basic design of our eye is a triumph of evolution, though other animals can actually see "better".
And while our eye is indeed a remarkable device for sensing our world, it's not necessarily the right adaptation for other creatures in other environments. For example, the horseshoe crab's system of multiple complex eyes has served them well in their environment for hundreds of millions of years.
Insects can see in ultraviolet light, and view spider webs in different (and apparently attractive) colors depending on how the web is assembled. Some spiders, like the garden and golden orb spiders, take advantage of this by building a web which supposedly looks to an insect like it either has a big flower in it (garden spider), or has a big hole in it (golden orb). That zig-zaggy weave you can see in the photo is the focus of research; it's called a "stabilimentum".
Other creatures, like crustaceans, cuttlefish and squid, are sensitive to polarized light. They use this adaptation to find "invisible" prey which is transparent in normal light, but whose bodies alter the polarization of the light as it passes through them. Squid (and likely cuttlefish, too) also use this adaptation to view chromatophoric messages sent from each other.
A tiny transparent oceanic snail has an elongated retina which captures images line by line, like a TV picture.
And, of course, we're familiar with how some creatures see better in the dark than others. If you look at sharks' eyes, you can usually tell at a glance if they're a deep water shark (like the solid dark eyes of the blue shark or six-gill shark) or a shallow water shark (like the cat-eyed reef shark, or the nurse shark).
I'm sure you've seen those time-lapse films of starfish and brittle stars scuttling about in search of food. Pretty cool that they live in an entirely different time frame than we do, but they also see things differently than we do.
Ever look close at a brittle star? REAL close?
The crystalline structure which comprises the body of the brittle star acts both as armor and as a complex eye. Their body is covered with thousands of tiny light-collecting lenses which focus light onto photoreceptive cells lying beneath.
The cumulative input of those receptors gives the brittle star a rough image of its surroundings and helps give it a sense of the time of day. Scientists are studying this creature to apply its evolved microlens design to human optical networking and microchips.
And, speaking of eyes - as an FYI observation - have you taken a good close look at the eye of a mullet? Check one out in Bays & Beaches when you're in there. It has an unusually large clear membrane which covers everything around the eye and then some, BUT it doesn't cover the pupil, which is mostly covered by a slit-like eyelid.
February 2002
If it looks like a duck, and quacks like a duck - will you still hear an echo?
On one of my business trips to Guatemala last year, I advised my client at one point to get all his ducks in a row. He responded with "yes, but we have only one duck."
So, if that duck quacked on a canyon lake, and there was no one around to hear it, would the quack still echo? And if it did, how would you know it wasn't just another duck?
You may be asking yourself, just what has Jeff been smoking?
Given the rowdy reputation of the internet, it's still amazing how normally skeptical people will accept - unquestioningly - information they receive in e-mails. Currently making the rounds - again - is the silly e-mail where it's said that "a duck quack does not echo, and no one knows why..."
Who is "thinking" this stuff up? Now you may be asking yourself - what are THESE people smoking...and where can I get some?
Yes - duck calls will echo, quack or no quack. Not that all ducks actually quack anyway. Wood ducks whistle. Ruddy ducks cluck (try to say that 3 times real fast). Muscovy ducks wheeze - and poop everywhere (but I digress).
Ducks can not waddle past the laws of physics. Their calls, like any other sounds, will reflect off a hard vertical surface, and echoes will be audible if the calls are loud enough. You don't normally hear echoes in a marshy or otherwise vegetative environment, though, and that's where ducks typically hang out.
The bottom line is, quacks have no special stealth qualities known to science.
If you should receive an e-mail from gullible friends about anti-echo duck quacks (and you probably will eventually), do your part to edify by providing them this link and this one.
Let the truth be known. There's no question about this. We have the evidence. Duck calls and their echoes have been recorded (on duck tape, of course).
December 2001
Later 'Gator
Gators, like cows, are a commodity. And, like cows, just about every piece of a gator is used as a commercial product.
Apart from the typical "alligator tail" found in restaurants and alligator purses and other leather goods, alligators are also used for suntan oil and cosmetics. You can even buy "gator jerky". Their blood is used to test blood machines at medical facilities. Whatever's left goes for dog food.
Every couple of years or so you'll see mention that we're changing out our gators for smaller ones. The reason is that, although big gators are more awesome and make a greater impression on visitors, they're more hazardous to keep and much less active. And probably more expensive to feed.
In the wild, a baby gator will typically grow about a foot per year in its first 6 years. In captivity, though, a well cared for baby gator can grow up to THREE feet in a year. So we don't get to keep them very long.
Where do our gators go after they leave the aquarium? Well, back to the "farm". For the males, the farm is gator paradise, with two girls for every guy. But all good things must end, for both sexes - E I E I uh oh... When they get to be about 5-6 feet long they're "harvested".
October 2001
Secrets of Horseshoe Crabs
While beachcombing in shallow water during our kayak outing, we happened upon a male horseshoe crab in the sand. I tried to pick it up, which proved surprisingly difficult. Turned out he was grasping a buried female, and was not about to go without a fierce struggle.
I had unwittingly committed crabbus interruptus, and returned him to his biological urges once I had pointed out some things to the others standing nearby. Some questions came up which prompted this latest Things That Make You Go Hmmm...
Though not real crabs, horseshoe crabs shed their shells as they grow. The vast majority of those shells you find washed up on the beach are molts, and not dead horseshoe crabs.
Horseshoe crabs have existed in essentially the same form, defying evolutionary changes, for the past 250 million years. That's about twice as old as the Jurassic dinosaurs, and is a clue that these critters are keenly adapted to their environment.
About half the drugs we use to fight infections come from, or are based on, compounds made by plants or animals. Marine organisms have already provided a number of medically important products.
The horseshoe crab has a unique and simple defense against disease and injury. Their blood cells are programmed to burst when they encounter bacteria, releasing enzymes which cause a blood clot. The clot effectively forms a barrier which traps the invading microbes; the microbes are then finished off with an anitibiotic which is also released when the blood cell ruptures.
This biological advantage was not lost on human scientists at the Marine Biological Laboratory in Woods Hole, Massachusetts, who discovered after 30 years of research that a reagent used to test for bacterial toxins, called LAL (Limulus amoebocyte lysate), could be derived from the blue blood of horseshoe crabs.
Many fishermen specialize in horseshoe crabbing, and in certain areas of the northeast the horseshoe crab must be protected from overfishing. Why? Because the primary fishery use of horseshoe crabs is to provide bait for the eel and conch fisheries. Virtually the entire catch of the eel and conch fisheries is exported to Asia and Europe.
Other fishermen sell live horseshoe crabs to drug companies, which draw blood and then release the animals back into the ocean. This nonconsumptive aspect is being threatened by the other commercial interest in this animal.
Researchers draw blood by taking advantage of another horseshoe crab defensive mechanism. When threatened, the crab folds its shell together to protect its body. On the outer exposed hinge of the shell is a membrane which leads directly to the animal's heart area. When the lab animal folds up, it's put into a narrow water-filled trough which preserves that position and a needle is inserted through the membrane to draw the blood.
The blue reagants made from their blood provide a valuable test for gonorrhea, spinal meningitis, and the toxins that cause septic shock (which previously led to half of all hospital-acquired infections and one-fifth of all hospital deaths).
The reagents are also used to screen for bacterial contamination in drugs and intravenous equipment. During screening the reagent gels into a clot if it reacts with microbes, alerting the technician to the contamination.
For an excellent article on horseshoe crabs and LAL, click here.
August 2001
(International Version)
It's a smalla world in Guatemala
Something interesting happened recently, a thousand miles away.
The Florida Aquarium's intrepid interpreter and Lonely Planet explorer, Jonathan Frederick, was on a trek in Central America. I had just returned from there.
I received an e-mail from Jonathan which he'd written on a rented computer in a little internet shop in Guatemala. It began "funny thing... i could have sworn i saw you in the distance in panajachel a few days ago..."
We soon confirmed without a doubt that we had coincidentally passed within feet of each other in Panajachel, a little lakeside town nestled within the crater of a scenic ancient volcano in the isolated Indian-inhabited highlands of Guatemala.
I remembered seeing someone there who resembled him. He was unshaven with his nose deeply buried in a book (I never saw him look up, which would have helped me realize who he was). He was equally unsure of what he'd seen after he looked up and saw me at a distance.
Neither of us expected to see each other in such a remote area; and both of us were thinking "could that be......NAH!"
July 2001
| How Do Dolphins Breathe While Asleep? |
We continue our venture into the fascinating lives of dolphins....
Cetaceans spend their entire lives at sea. Bottlenose dolphins, based on electroencephalogram (EEG) readings, spend an average of a full third of each day asleep. The act of breathing, normally an automatic function, becomes a challenge when you're underwater and want to catch a few zzzzz.
Marine mammals, like dolphins, rarely actually drown, since they don't inhale underwater, but they can suffocate. To avoid suffocating while asleep, cetaceans must maintain conscious control of their blowhole, the flap of skin which opens and closes in a voluntary act of the animal. How do these creatures sleep and breathe at the same time?
Observations of bottlenose dolphins in aquariums and zoos, and of dolphins in the wild, have shown two main methods of sleeping: they either rest in the water, vertically or horizontally, or sleep while swimming slowly next to a buddy.
Individual dolphins can also enter a deeper form of sleep (called "logging") - mostly at night - where they actually sleep at the surface.
Being born underwater can be a problem for whale and dolphin calves. It's apparently the sensation of air on skin which triggers that initial crucial breath, so the first step is to get the newborn immediately to the surface.
Young whales and dolphins rest, eat and sleep while their mother swims, drafting along in her slipstream in a behavior called "echelon swimming". The mother can also snooze while echelon swimming, and doesn't stop swimming for the first several weeks of a newborn's life. Since the calf isn't born with enough body fat or blubber to float easily, it'll sink without Mom's help. And lots of swimming will tire a youngster, of course, which can produce a weak animal susceptible to infection or attack.
Adult male dolphins, which typically travel in pairs, often swim slowly side by side as they sleep. Females and young travel together in protective larger pods. They may rest in the same general area, or companionable animals may pair off for sleeping while swimming.
Here's something particularly interesting - while sleeping, the bottlenose dolphin shuts down half its brain, along with the opposite eye. The other half of the brain stays awake at a low level of alertness. The attentive half is used to watch for predators, obstacles and other animals, and helps the animal know when to rise to the surface for a breath of air. After approximately two hours, the animal reverses the process, resting the formally active side of the brain and awakening the rested half.
Dolphins generally sleep at night, a couple hours at a time, but they also have active periods where they feed on fish and/or squid in the inky nocturnal depths.
Rapid Eye Movement (REM) - a characteristic of deep sleep - is hard to discern in these critters. But some research shows that cetaceans do undergo dream sleep.
Marine mammals have also adapted other changes to hold their breath longer than other types of mammals can. They can take in more air with each breath, because their lungs are proportionately larger than those in humans.
In addition, they exchange more air with each inhalation and exhalation because their red blood cells also carry more oxygen. And when diving, marine mammals' blood travels only to the parts of the body that need oxygen - the heart, the brain and the swimming muscles. Digestion and other bodily processes are put on hold.
And if you've read the link on the Cool Links page on dolphin physiology, you know that dolphins save their oxygen when diving deep by compressing and sinking like a rock instead of swimming down to where they want to go. (And if you haven't read that article yet, check it out - there's some very interesting info in there).
The brains of these animals also have a higher tolerance for carbon dioxide, and don't trigger a breathing response until the levels of CO2 are much higher than what humans can tolerate.
If unable to reach the surface, or if in a panic, the animal may dive deeper, where it will be unable to breathe, and suffocates. This is especially problematic with fishing nets.
June 2001
This month I have a lighter mixture of oddball things to share which may actually make you go hmmm for different reasons than before.
Great Moments in Shark Feeding
While many of you may be familiar with the recent Florida Fish and Wildlife Conservation Commission decision to continue to allow shark-feeding dive excursions in our waters, how many of you know that one of the pioneers in this underwater tourist trade did some of these dives half-naked?
The first commercial operation to feature reef-situated, non-cage shark feeds was reportedly Herwarth Voightman's grey reef shark feeding dives in the Maldives. These apparently were very popular with European divers in the early 1970s for a variety of reasons, and not necessarily just for the thrill of experiencing a "Jaws"-like shark feeding frenzy.
European sensibilities regarding nudity are substantially different from ours, and so it came about that divers visiting from the continent would be treated to shark feeds conducted by Voightman's daughter while she dived topless.
Taking the regulator out of her mouth, she would hold her breath, place the tail of a dead fish between her teeth, and lean forward to entice the sharks into taking the bait.
Several near-accidents, reportedly involving intimate brushes with sandpaper-rough sharkskin and the scrape of teeth across sensitive body parts, finally convinced the exhibitionistic lady diver to treasure her chest and conceal the doubloons.
Wide Fracture of English Possible
A Korean fish-slicing machinery company has an English-language website which describes its products with the following examples of good English gone very bad:
[This is] "an delicately-cutting machine of a squid pickles"
[This machine is] "made exclusively for thin squid of tear possible, it can be used for thick squid of tear possible, too."
Tastes Great, Less Filling, and More Obnoxious to Octopuses
An octopus den can often be identified by a pile of discarded mollusk shells or crab and lobster exoskeletons out front. One trick to coax an octopus out into the open is to fill a plastic squirt bottle with water and rock salt and then squeeze the hypersaline mixture into the den.
But some fishermen in Bermuda reportedly have another trick up their, umm, sleeve. To perform the same act - but in a more entertaining way - they drink a lot of beer, wait a bit to build up sufficient bladder pressure, then dive down to a known octopus hangout.
Upon arrival the diver urinates into the octopus' formerly safe haven, flushing - so to speak - the stressed cephalopod out for easy capture.
And that Ink? It's not what you think...
OK, so let's get more scientific here. What's that black stuff the octopus shoots out when it's frightened?
Cephalopod ink, called sepia, was used in the past for writing ink and artist's paints. It's actually a mixture of melanin - the pigment that gives the ink its color - and mucous.
The mucous gives the ink its shape by hold the melanin together in salt water. A dense ink blob which serves as a decoy has more mucous in it while a larger ink cloud, which serves as a smoke screen, has less.
Cephalopods can control the shape, size and placement of the inky mucous with their funnel. And there is anecdotal evidence that there may be something in the ink or mucous which interferes with a fish's sense of smell.
Most octopus species are born with a fully-functional ink sac; deep sea octopuses, though, don't have one at all.
It's well-known that the octopus also protects itself through camouflage, changing the texture and color of its skin as it sees fit. And of all the colors the octopus can display, white or red identifies a stressed animal.
And if it's yellow - it could be a stressed Bermudan octopus.
May 2001
Some Oddball Shark Facts
CLASPER ENVY
Male sharks have it made. Not only can they use tonic immobility to get an easy date, they also have two sexual organs. Called “claspers”, these organs are kinda special and have some unusual characteristics.
The same hard material which comprises shark teeth also comprises a shark’s scales (called denticles). And each clasper has a distinctive modified scale at its end.
This hook-like scale is so unique that a species of shark can be identified from that scale alone. The scale "hooks" inside the female when the clasper is unrolled and inserted, and the clasper can not be withdrawn until delivery is made. No coitus interruptus in the shark world. No sirree...
And why do male sharks have two claspers? Well, for one thing, claspers are actually modified and calcified pelvic fins, which come paired to begin with. But the dual nature also aids the male in getting into the proper position with a female. It's helpful to have a clasper on either side whenever that brief opportune moment with a willing partner arrives.
In many species the female's skin is nearly twice as thick as the male's, because the male apparently feels a need to munch down on the female's pectoral fin to get some leverage so that he can roll her over. If you've ever seen nurse sharks mating you'll know what I mean.
The male shark is also equipped with an organ known as a siphon sac; the sac fills with water, and the pressure exerted by the water forces sperm down through a groove in the clasper and into the female.
SLIPPERY SHARKS
If you've ever "petted" a shark, you know that it's a lot easier to rub your hand from head to tail than vice versa, the reason being that the shark's denticles are mainly curved upward and to the rear.
Research has shown that shark denticles are also arranged in tiny V-shaped groove/ridged patterns known as "riblets".
Because it's been shown to lessen air drag on plane wings, the riblet configuration is of considerable interest to aircraft designers. The naturally-designed denticle riblets on a shark serve a similar function underwater, lessening drag on the shark as it swims.
TONIC IMMOBILITY
Reportedly discovered by former stunt diver and now resort owner Stuart Cove in the Bahamas, tonic immobility (TI) is one of those "things that make you go hmmm" in the shark world.
Cove was taking hooks out of the mouths of silky sharks which gather around a US Navy submarine sonar testing buoy. He observed that by holding and curving a silky's tail, then deftly turning the shark over and holding the dorsal fin with the other hand, it would go into a trance and just lay there, holding still in a state of near-paralysis for a period of several minutes without harm to the shark or himself.
Many other shark species (like the tiger shark) are also susceptible to TI. It's not yet known whether this also works on great whites; for some reason, as far as I can tell, no one's been curious/brave/dumb enough to test the technique on them...
Anyway, the theory is that tonic immobility evolved as part of the mating ritual of the shark.
Bear in mind that caution is still warranted even with a snoozing shark, because beneath every functioning tooth in its mouth are sensitive nerve fibers which stimulate a reflex action, causing the jaws to close whenever any pressure is exerted on the tooth.
This reflex action can occur even after the shark appears to be dead, so it's a really good idea to keep your hands well away from any shark's mouth or snout - dead, alive or immobile.
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