The “Walking” Elasmobranch

Sunday, 15th of April 2012

Walking behavior in the clearnose skate (Raja eglanteria)

One of the most difficult tasks of a wildlife filmmaker is the patience required to capture the right moment. Inspired by my friends who had filmed a pair of seahorses mating the previous day, I set out to spend every single breath of my air tank to capture similar imagery. Of course, nature does not follow any specific schedule. Things can happen at any given moment.

Studies have shown that many species of seahorses are monogamous throughout the breeding season and their courtship dance can last up to eight hours. Their amorous ways can repeat for multiple days. Armed with this bit of information, I was hopeful to capture the seahorse’s mating behavior. To do so I was prepared to spend some quality time watching these two love-stricken seahorses.

I linger a comfortable distance from the seahorse’s post twenty feet below the ocean’s waves; a depth that would grant me plenty of bottom time. Meanwhile, the seahorses glance at each other ever so tantalizing. Had nature gifted them with eye lids, certainly there would be a lot of winking involved.

Minutes roll across my dive computer, but still the seahorses do not budge. I second guess myself numerous times wondering if it is not in my best interest to swim around in search of other marine treasures and leave the rest up to fate. After all, my time underwater is limited by my air supply and the ocean’s tidal flow. I decide to give in to my uneasiness, at least partially, and begin to comb the nearby area for creatures that fancy my attention. All the while I glance up to observe the seahorses every few seconds.

Numerous creatures begin to appear from a desolate-looking landscape. Hiding beneath a shell, a squat lobster the size of my finger nail is poised with its elongated claws like a chivalrous knight defending the castle.  A psychedelic-looking nudibranch, close relatives of terrestrial slugs and minuscule in size, glides up and down the equivalent of mountainous algae tufts. The nudibranch’s vibrant colors signaling to other creatures of its unpalatable qualities.

Clearnose skate (Raja eglanteria)I swim over a bleak prairie of sand painted with the dappling rays of the sun. Scanning this sandy patch of ocean, my attention is captured by a small pattern in the sand that did not match the sand’s ensemble. A leopard-like pattern begins to manifest itself as I carefully fan the sand from above this unknown creature. Its image slowly begins to reveal itself. A diamond-like shape unequivocally leaves me guessing it is in the ray family; a clearnose skate (Raja eglanteria) to be exact.

The skate awakes in an explosion of sand as I attempt to take its photograph. Fifty yards pass before this creature finally gives haste to my chase. By now my air supply has taken a drastic hit and my mind whirls as I prepare both of my cameras to capture the skate’s image. The red light on my underwater video camera blinks as the clearnose skate begins to move along the bottom in a slow and steady pace. But something is different about its movement.

Unlike most rays who use their pectoral fins or “wings” to propel themselves, this remarkable creature has somehow adapted to “walking” along the ocean floor. He does not need to use his pectoral fins for locomotion. Instead, using a pair of modified pelvic fins, internally shaped very much like a thigh, a calf and a foot, the clearnose skate has evolved the ability to walk along the benthic environment in which it lives.

Clearnose skate range (Raja eglanteria)What purpose does this evolutionary quirk serve the clearnose skate that would make him evolve differently than many others in his elasmobranch (sharks & rays) family? Being a sand dweller who hunts using a set of electroreceptors in its body, perhaps this means of locomotion allows him to finely hone his ability to detect and approach his prey. Conservation of energy is certainly another possibility.

Such tetrapod-like limb movement even challenges the evolutionary theory of the first animal to clamber on to the land from the sea; considering that elasmobranchs have been on Earth for close to 500 millions years. Modern day animals such as this clearnose skate might provide a clue to our evolutionary past.

Capturing the natural history of an animal at the right moment offers many challenges to a wildlife filmmaker. While the rewards of capturing the true, wild nature are partly self-indulging, there is also the possibility of glimpsing into our own past, and certainly our future, in the animals we film. While we might not get exactly what we’re after, nature seems to alway hint at us at all her secrets and splendors.

 



Think Outside The Sub

Sunday, 13th of November 2011

Juvenile lookdown fish with moon jellyfishThe weather Gods have certainly been upset with us in Palm Beach lately. For the past two weeks it has been extremely windy producing big seas and very poor visibility. Reaching the one month mark since my gills have been properly soaked in any salt water I was ready to get in the water no matter the conditions. Along with five other determined divers, we motored out the Lake Worth inlet aboard Sirena.

North of us we could see hundreds of birds diving into the water; a sure sign that there was a lot of action going on beneath the waves. One diver, in an attempt to find some blue water, mentioned the possibility of doing a blue water dive in a couple hundred feet of water. Everyone on board agreed and so we motored out into the abyssal blue with no ideas as to what we would find.

At around 230 feet of water we jumped in and hovered around 20 to 30 feet. At first, the hazy blue water seemed devoid of life, but it wasn’t long before life began to make its grand appearance. Moon jellyfish, who have been very numerous this year, drifted in the water column. That was my cue to begin my search for the rare and unique, for many animals hitchhike amongst the many pelagic jellyfish that circle our world’s oceans.

I looked closely at each one in hopes of finding the rare argonauts, a type of pelagic octopus, that the strong east winds tend to bring off the Gulf Stream. Within minutes a sight I had never seen before appeared before my eyes. A fish, smaller than the palm of my hand, hovered near the stinging tentacles of a moon jellyfish.

Juvenile lookdown fish in deep waterHaving a closer look at this tiny creature, I could make out a gorgeous set of appendages. Trailing from its dorsal and pectoral fins were a slew of intricate-looking decorations. As it swam towards me, its pectoral fins reminded me of the elaborate design of the leafy sea dragon seahorse found in Australia. I dared not pass up the opportunity to photograph this wonderful looking creature.

Most of the dive was spent following this tiny fish, who I later was able to identify as a larval lookdown fish (Selene vomer), all the while looking around me in this vast blue abyss for other creatures who might escape my attention. One almost did if not for the weary eyes of another diver who pointed it out to us. Out from the hazy distance, a tiny three foot apparition darted towards us; a silky shark. Curious to know what strange, noise-making animals were intruding on his environment it took one quick look around, swimming around each of the divers, and just as quickly as it appeared it disappeared again. We would only see it one more time during the long and exciting forty-five minute dive in the blue abyss.

While conditions were far from ideal for a dive, thinking outside of the box sub made what would have likely been another regular dive into something extraordinary. The ocean never fails to excite and enthrall. Never give up any opportunity to experience nature in its raw form, no matter the conditions.



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