Verrafjord, Norway
Blue and white with a smart yellow stripe at her gunwales, a sleek little ship cruises south on calm seas, along the mountainous coast of Norway. To her west rocky islands break the surface; most of them are low and rounded but a few rise to dramatic peaks, echoing the coastal highlands to the east. It’s a sunny afternoon; only a light wind ripples the surface of the sea, a tranquil and familiar scene. But close by, on the shoulders of the islands beneath the dark water, a drama of life and death plays out and strange miracles are achieved with unconscious nonchalance.
Sixty feet below the waves, on a rocky buttress, a nudibranch, a beautiful sea slug, is slowly crawling out the stem of a flower-like hydroid. The stem is tough, well defended and uninteresting to the slug, but at it tip blooms a beautiful head of delicate feeding tentacles and reproductive buds. Now within range, the slug pounces (as well as a slug can pounce, anyway) and seizes the hydroids crown in its muscular mouth. Immediately the nudibranch’s many rasping teeth begin grinding through its prey and in a few moments the hydroid is decapitated and the slug relaxes, well fed again.
But nourishment is not all that the pretty little mollusk takes from its hydroid food. Climbing out onto the hydroid stems exposes the nudibranch to view and the risk of becoming prey itself, but it has evolved an astounding defense. The tasty tentacles of the hydroid are armed with nematocysts, toxic harpoon cells, cocked and ready to fire at the slightest touch. The hydroid employs these both for defense and to capture it’s own prey, but the slug is immune to their sting. In fact it is able to carefully consume them without triggering their stings. This is impressive enough, but what the nudibranch does next is truly miraculous. The active nematocysts are passed through its gut and then incorporated into the tissues of its gills, delicate projections that cover the dorsal surface. Thus, the nudibranch co-opts its prey’s defense for it’s own purposes, becoming a stinging slug without having to make the stinging cells for itself.
It’s an incredible achievement of transplantation. In our crude surgical swapping of organs and tissues, careful matches of donor and recipient are necessary and many times transplanted organs are rejected, even if they come from close familial relatives of the recipient. The sea slug, on the other hand is able to consume tissue from a creature on a distant branch of the animal family tree, pass the cells through the wall of its gut and transform them into active parts of it’s own body, without any risk of rejection!
Meanwhile, sixty feet above, the little blue ship sails on, cruising toward more lovely scenery and more of the everyday miracles of our little blue planet.
Blue and white with a smart yellow stripe at her gunwales, a sleek little ship cruises south on calm seas, along the mountainous coast of Norway. To her west rocky islands break the surface; most of them are low and rounded but a few rise to dramatic peaks, echoing the coastal highlands to the east. It’s a sunny afternoon; only a light wind ripples the surface of the sea, a tranquil and familiar scene. But close by, on the shoulders of the islands beneath the dark water, a drama of life and death plays out and strange miracles are achieved with unconscious nonchalance.
Sixty feet below the waves, on a rocky buttress, a nudibranch, a beautiful sea slug, is slowly crawling out the stem of a flower-like hydroid. The stem is tough, well defended and uninteresting to the slug, but at it tip blooms a beautiful head of delicate feeding tentacles and reproductive buds. Now within range, the slug pounces (as well as a slug can pounce, anyway) and seizes the hydroids crown in its muscular mouth. Immediately the nudibranch’s many rasping teeth begin grinding through its prey and in a few moments the hydroid is decapitated and the slug relaxes, well fed again.
But nourishment is not all that the pretty little mollusk takes from its hydroid food. Climbing out onto the hydroid stems exposes the nudibranch to view and the risk of becoming prey itself, but it has evolved an astounding defense. The tasty tentacles of the hydroid are armed with nematocysts, toxic harpoon cells, cocked and ready to fire at the slightest touch. The hydroid employs these both for defense and to capture it’s own prey, but the slug is immune to their sting. In fact it is able to carefully consume them without triggering their stings. This is impressive enough, but what the nudibranch does next is truly miraculous. The active nematocysts are passed through its gut and then incorporated into the tissues of its gills, delicate projections that cover the dorsal surface. Thus, the nudibranch co-opts its prey’s defense for it’s own purposes, becoming a stinging slug without having to make the stinging cells for itself.
It’s an incredible achievement of transplantation. In our crude surgical swapping of organs and tissues, careful matches of donor and recipient are necessary and many times transplanted organs are rejected, even if they come from close familial relatives of the recipient. The sea slug, on the other hand is able to consume tissue from a creature on a distant branch of the animal family tree, pass the cells through the wall of its gut and transform them into active parts of it’s own body, without any risk of rejection!
Meanwhile, sixty feet above, the little blue ship sails on, cruising toward more lovely scenery and more of the everyday miracles of our little blue planet.
