Loggerhead Hatchlings on the Way to the Sargassum Fields

Hatchling loggerhead turtles dig themselves out of the sand on the beaches of Florida and hurl themselves into the Atlantic Ocean in search of the North Atlantic Gyre, a circular current, which takes them to the undersea meadows of the seaweed sargassum. There they hide and eat and grow until they are big enough to fend for themselves in the open sea and eventually migrate back to their hatching grounds. If they miss the gyre, they will in all likelihood die. How do the hatchlings know that the gyre means safety, and how do they find it? They have no mother turtle to take them along and show them where to go, have no experienced turtles to swim besides.

Like other migrating animals, the baby turtles have the ability to navigate by the electro-magnetic field of the earth. They can intuitively combine the magnetic information about latitude (magnetic fields get stronger at the poles), and longitude (the angle of the pull of the magnetic field lines that intersect the Earth changes) and figure out where they are, as scientists have discovered recently. However, imagining them computating positional information and calculating mathematical coordinates as if they were scientists or nautical engineers is probably not the way it works. Or saying simply “its instinct” is also not very helpful because that does not explain anything. Is there a better way to explain how the baby turtles find the sargassum fields hundreds of miles away in the middle of the Atlantic after they hatch alone in the dark on a Florida beach?

The hatchling turtle has a mother who has laid the eggs and who herself hatched many years ago and went on the same journey just as her mother had before. Our baby turtle is part of a long line of sea turtles that perfected surviving in this particular environment. Over thousands of generations, each single one knew what to do without any example or instruction from other members of its species. Knowledge, for these turtles, is not something learned, at least initially, but they are born with the basic capacity to find the gyre and the safety of the sargassum meadows. This knowledge, however, is not fixed like a map in the brain. It is not a mechanical instinct which responds automatically to a set of stimuli. Rather, it is an open ability to grasp the varying patterns of shifting magnetic fields, the force of currents, the temperature of the sea, the variations in light and darkness and adapt its swimming body to it. This openness to its particular sensory world is a hallmark of the turtle’s mind. The turtle mind is a genius in reading the variable semiotic patterns produced by the deep sea environment, make sense out of them, and adapt its behavior accordingly. Baby turtles are already perfectly equipped to respond sensitively to shifts within this environment as they traverse it. The Atlantic Ocean is their milieu, and it is a complicated world of currents that caress the skin, patterns of light that hit the eyes, predators who bar the way, food that beckons – movement of all and sundry that communicates itself directly through the undulating water against the hatchling’s body.

It is ultimately unimaginable to humans what the world is like for the small loggerheads, but even from brief attempts to feel our way into their sensory world we can guess that that watery world is very differentiated and subtle and that the hatchlings’ bodies have fully functioning sense organs that can respond to its demands. We cannot really grasp what it is like for the sea turtle to experience shifts in the angle of latitude because we humans have no way to perceive something like this. But turtles have sense organs which perceive magnetic fields. They can feel them, like we can feel warmth on our skin or see the colors of the rainbow. We have no comparable sense-organs to make sense of this kind of experience: it is beyond the realm of human perception, and the experiential range of our bodies does not encompass most of the sea turtle’s floating, watery lived world. Our empathy with it is limited, our understanding of it is laborious and rough. Every turtle, on the other hand, makes sense of the sophisticated patterns of currents and magnetic fields, and the species finds its way in the ocean world with ease.

The desire for the North Atlantic Gyre is inscribed into the loggerheads’ bodies and pulls them through the sand and into the open sea as soon as they break their eggshells: they are designed to find it. The fit between body and milieu is an intertwined structure, and the turtle has a basic a priori knowledge or sense about what actions are good and beneficial for survival. The turtle’s knowledge, I imagine, is not so much rational and logical, but intuitive and aesthetic. It swims towards what feels right and good. This aesthetic knowledge is not a function of individual experience and personal memory, but of the body itself and belongs to the basic equipment of all organisms. Organisms judge the shifting patterns of their particular worlds to be good or bad. Instinct (if we choose to retain this term) for the turtle is not a fixed pattern of behavior, but a functional, open ability to respond to structural changes in its milieu and judge their value. As the shifting magnetic fields move across the turtle’s magnetic sense organs, they structure the perceptual field in meaningful ways: here is the good direction, but there is the lack of pressure that needs to be avoided; this way feels right, but that way feels anxious. The turtle’s body knows when to push the flippers to the left and tilt the shell to maintain course toward the gyre, which, as it knows in its bones, is the ultimate good. It adjusts its senses continuously, keeping the telos, the goal of all desire, in mind. Guided by knowledge and desire, it can “read” the flux of magnetic patterns and currents as its swims along the earth surface and adapts its body to them. All its actions, from the beginning, are already constituted by the distant North Atlantic Gyre, which, once found, swirls it along in its wake and deposits it in a place of safety, nourishment, and rest.

Filed under: Eva-Maria Simms, Nature, Prose