Glowing Strands of Strangeness
Strange creatures have been washing up on the shores of Cannon Beach. Several gelatinous species have stranded recently, including the barrel-shaped blob in these photos: a salp.
Though salps resemble jellyfish without tentacles, they belong to a group called tunicates. Tunicates in their larval stage have a kind of primitive backbone—making salps more closely related to people than to jellyfish. Sometimes I stare at a blob of salp goo on the sand and let this bizarre fact bubble in my brain.
Salps may look like lumps of limp gelatin when they’re stranded on the beach, but in the ocean these creatures pump water through their transparent bodies, moving by jet propulsion as they feed on phytoplankton in the seawater they filter. In turn, salps are eaten by siphonophores like the Portuguese man-of-war, seabirds, fish, and sea turtles.
This gelatinous animal I found on the beach represents one part of a strange lifecycle that involves both solitary salps and salp aggregations. In its solitary phase, a salp reproduces asexually by budding a chain of clones that create light. The individual salps in a luminous chain remain attached as they swim. These strands of glowing strangeness can stretch for more than fifty feet. The chains of some species take on complex shapes such as giant wheels, and even a double helix.
After the chain phase of a salp’s lifecycle ends, things really get interesting. Each member of a salp chain is a sequential hermaphrodite. A salp starts life as a female and then turns into a male. When a chain breaks apart, the individual salps reproduce sexually. Older salps that have turned into males fertilize females; as females that have been fertilized grow older, they transform into males that fertilize younger females.
A fertilized salp female produces an embryo. Then the embryonic salp emerges from the mother and grows into a solitary creature that buds its own chain of clones—which are sequential hermaphrodites that reproduce sexually. And so on, in one of the many mind-bending lifecycles of ocean creatures. We may one day travel to distant worlds and discover forms of life that don’t seem as otherworldly as a glowing salp chain using jet-propulsion to power its way through Earth’s oceans as it feasts on the tiniest creatures in the sea.
Asexual cloning is an extremely fast form of reproduction. But it can lead to an evolutionary dead end because it doesn’t result in the genetic diversity a species needs to adapt to changes in the environment. Sexual reproduction creates genetic diversity within a species—but it’s a slow way to reproduce. Our salp cousins have arrived at a strategy that combines the best of both reproductive methods. When food sources are abundant, salps clone themselves in tremendous numbers to take full advantage of the bounty. And because of the constant gene shuffling that comes with sexual reproduction, when the environment of a salp species changes, some individuals will have the genetics necessary to survive the shifting conditions.
We have explored less of the ocean floor than we have the surface of Mars. Think of the strange beings yet to be discovered in the saltwater of our planet. There is no end to the weirdness beneath the waves, and each gelatinous creature stranded on the shore tells a story of survival and adaptation in the watery world where our own species began.
On another note, salps aren’t terribly photogenic, but they can be fun to shoot when light reflects and refracts as it passes through their gelatinous bodies. The clear tunic of a salp acts as a sort of prism and a primitive lens, magnifying sand and breaking white light into bright colors. Who needs drugs when salps are washing up on the beach bearing rainbows in their alien bodies.
The salp species in these photos is probably Cyclosalpa bakeri. “Cyclo” comes from the Greek word for circle or ring. Cyclosalpa individuals join together in circular chains that whirl through the ocean.
When you see a jelly blob on the beach, imagine a chain of salps joined in a glowing circle wheeling through the dark of the deep ocean. Salps evolved on this planet long before our big brains evolved; salps will likely be here long after our brains have either figured out how to be good stewards of this planet or have annihilated most complex life on Earth, including our own species.