Beachgoers and ocean explorers have been greeted by an estimated countless bazillions of salps caught up in current events, including these donut salps, Cyclosalpa affinis, found just offshore of the Aquarium last week!
Salps are prolific and prodigious filter-feeders and key members of the gelata—the myriad different gelatinous, drifting organisms that make up a significant part of the ocean’s mass of living creatures. Most salps have a bewildering life history that these cyclosalps illustrate beautifully.
The solitary phase of the salp is known as an oozooid—it will asexually produce long chains of clones known as gonozooids that you can see emerging in the photo above.
Now Cyclosalpa gonozooids aren’t just sexy plankton for their enchanting bouquets, oh no no—in this phase, most salps are sequentially hermaphroditic, starting off female with an egg that is fertilized by older, male individuals from other chains.
The embryo develops into an oozooid inside its sexually-reproducing parent—and those developing oozooids may already be growing their new clone chains before they’ve even flown the gelatinous nest! You can see the next generation developing inside these older gonozooids:
This alternation of generations enables salps to be some of the most productive organisms in the multi-cellular world, exploding in numbers overnight and drastically altering the planktonic landscape by feeding on a wide range of food sizes and starting blizzards of marine snow as sinking fecal pellets and food-stuffed mucous pours into deeper waters from the salpy deluge.
Salps are one of the ocean’s most influential biological players, and that’s not the only thing we share in common. Salps are invertebrate chordates, along with their tunicate cousins the pyrosomes, doliolids and sea squirts—those colorful reef-dwelling filter-feeders found throughout the world ocean.
These animals all look rather like we do in their early stages, with a notochord in their larval form that is largely lost in transition to adulthood in the tunicates, while being replaced in purpose by a backbone in fishes, birds and us mammals.
So as alien as salps may appear to be in their midwater manner, they’re some of our closest invertebrate kin—and a key part of the backbone of our ocean planet’s operations.