For a long time this gesture was a mystery to me, and I finally decided it was an expression of excited recognition, like the way dogs will joyfully run to you when you arrive home.
That they always approach my face, indicates their recognition of the frontal view. On the other hand, strange sharks will come from behind to take a closer look without being seen, or pass close by when I'm looking the other way. Often sharks will immediately react when they become aware that a person cannot see them, for example when one looks above the surface. Sharks appear to use the limits of visibility to remain out of sight when it suits them, coming just close enough to have a look once in awhile, and keeping track of the object of their interest by using their other senses (hearing and detection of vibrations in the water-medium). Thus they appear to be aware of being present and viewable. Similar behaviour has been considered in bears as an indication of self awareness (Donald R. Griffin 'Beyond Cognition to Consciousness' 2001). A variety of behaviours indicating thinking in sharks are described in my accounts of specific individuals, soon to be put on line on my planned website, which constitute some of the first observations of cognition in sharks.
In time I became familiar with their daily life habits, social lives, and reproductive cycle—the article reproduced on this site 'On the gestation period of the blackfin reef shark, Carcharhinus melanopterus, in waters off French Polynesia' was published in the journal Marine Biology.
Most males, who are smaller than the females, live on the outer slope of the barrier reef; it is the males you mostly see on shark dives. The lagoon is the usual domain of the females and juveniles, and so it was those with whom I became most familiar. Each shark has a preferred area, called the home range, and these ranges overlap. Sharks living in the same region know each other as individuals, and have companions they often go with when they travel elsewhere. This indicates that sharks recognize each other as individuals, and because they appreciate a companion, it was easier, I think, for me to be accepted by them as a companion.
On the few occasions when I came with another person, they responded by vanishing behind their curtain of blue, sometimes after coming quickly over to verify my identity. They could tell the difference between me and another human; in other words, they recognized me as an individual too. Besides involving learning and memory, such behaviour showed their awareness of changes in the routine or their environment, and their ability to make quick decisions.
One of the very large and apparently quite old females I met was very dark, with a pure white marking symmetrically placed on each side of her head. It looked as if someone had stuck two large snowflakes on her. Arriving always at dusk, she was a dramatic sight with the twin white points glowing bright. I called her Kimberley. She remained in the area for nearly a month, and before she left, I saw another very similar visitor. Not only was the patterning of their colour lines and dorsal fins alike, but this shark, too, had pale markings placed precisely the same way on her head. She also arrived as night fell, and I called her Twilight. Since none of the other sharks had this type of white marking, I speculated that the two sharks were sisters. It was months before either of them returned to the area, but there came an evening when the twin snowflakes approached through the gloom. Kimberley glided in, and the following week, I saw Twilight.
For three years I watched the two come and go every few months, sometimes together. Was it chance? Or was there an association between them? Finally, when Kimberley appeared again after months of absence, at nightfall, I went looking for Twilight and actually found her, following about a minute behind Kimberley. She passed me, and just then Kimberley appeared equally distant on my other side. The two sharks were arcing towards each other, as though following the same circle. They met in front of me, passing so closely they may have brushed each other. But though I watched intently, I discerned no sign pass between them. Maybe just the close pass was the important thing, each shark reaffirming 'we are here.' Twilight languidly cruised back and forth in a figure eight pattern, strangely not minding me staying with her. Time after time she caught up to another female shark who was already present, apparently intercepting and pursuing her trail of scent. Then the two would swim together briefly, usually, before moving on and joining another shark.
Kimberley and Twilight arrived together at dusk each time I saw them for the following month, reinforcing my theory that they were associated, and maybe sisters. They continued their sporadic visits until shark finning began here, whereon Kimberley immediately disappeared, and Twilight held out for awhile, before she too vanished. Nearly all of my beloved females were slaughtered within a few months when the killers from Singapore arrived here, and the government pondered over whether or not to let them devastate the country's sharks.
Clementine and Odyssey were large, elderly females. They visited the study area together in the dark of the moon at the end of April four years in a row, and at no other time. Cheyenne, who was in about the same age-group, accompanied them the two last years, but after the initial visit she returned alone every few months. This is one of the more exceptional examples of sharks following a surprisingly precise schedule as well as traveling with favored companions.
Companions apparently move in loose contact, regularly meeting and moving on for awhile together, either side by side or nose to tail, but most of the time out of visual range of each other. They make wide circles forming enormous figure eights or cloverleafs, ideal for intercepting scent trails. Odours that interest them are from other sharks as well as possible food sources it seems, and thus, as well as through their sensitivity to underwater sounds and vibrations, they can remain in loose contact as they travel.
One morning when I went outside at 5:00 a. m., a single white feather fell from the empty sky to lie upon the surface of the lagoon, and as if in a spell, two shark pups appeared. Apparently just out of the nearby nursery, they were scouting the area, their circles and turns creating a mesmerizing ballet, full of grace. Sometimes they swam separately, sometimes they followed each other; sometimes they swam after each other in a perfect circle, each with its nose six inches from the tail of the other. The school of baby tangs that lived in the shallows formed a little yellow cloud, pointing towards them as they passed. A mynah bird swooped down to look. Sometimes they followed other fish, sometimes other fish followed them. The rhythmic side to side motion, like a heartbeat, that typifies this most graceful creature, felt like a beat in their music. Though I had formed a theory about being able to estimate the size of fish from the ripples generated on the surface, the passage of these little sharks showed not a sign upon the glassy surface. At 7:20 the neighbours started trying to shoot them, and bragged all weekend of their fruitless efforts, as though they had taken on visiting monsters.
Presumably the babies got to know each other in the nursery, where they were born alive in shallow, protected waters, and may even have been siblings. Such long term companionships as I witnessed in adults, could conceivably have begun just like this.
After years of watching sharks in different situations and interacting with them, I think that their type of mentality urges them to get one step ahead of the object of their attention, clearly an advantage to predators who run down fish for a living.
No matter what happened, I was never bitten by any shark, though in intimate contact with most species, one is usually eventually bitten, whether it is accidentally by one's dog, or intentionally by an irritated parrot, mouse, or skunk. Sharks were the only type of animal I had intimate contact with who never bit me, and I came to believe that this species, at least, has a built in inhibition against biting companions.
It was one reason they became the favoured ones, of all the wild animals I have known. Never did they betray my trust and hurt me. No matter what happened or went wrong, time after time.
I hope my accounts will contribute to appreciation of sharks as the intelligent animals they are, counter shark attack mania, and encourage their conservation.
Ila France Porcher © 2006