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Salps on Dana Bay Beaches, washed up for three weeks during December.

The animals are salps, the species is probably Thalia democratic, one of the smallest species but one that occurs in large populations, often near the coast. Although salps appear similar to jellyfish because of the simple form of their bodies and their free-floating way of life, they are structurally most closely related to vertebrates, animals with true backbones, and are actually in the same animal phylum (Chordata) as we are. (We have had similar occurrences in the northeast US, when they wash up on beaches looking just like your pictures – Larry Madin, Marine Biologist, USA). There are two life stages of salps, the solitary and aggregate forms. The pictures are of the aggregate forms, which are normally connected together in chains, but are readily broken up in the waves.

A salp (plural salps) is a barrel-shaped, free-floating tunicate. Most species occur further out to sea and are not seen inshore. They move by contracting, thus pumping water through its gelatinous body. The salp strains the pumped water through its internal feeding filters, feeding on phytoplankton that it sieves out of the water, don’t sting and are completely harmless. Salps are common in equatorial, temperate, and cold seas, where they can be seen at the surface, singly or in long, stringy colonies. The most abundant concentrations of salps are in the Southern Ocean (near Antarctica). Here they sometimes form enormous swarms, often in deep water.

Salps have a complex life cycle, with an obligatory alternation of generations. The solitary life history phase, also known as an oozoid, is a single barrel-shaped animal that reproduces asexually by producing a chain of tens to hundreds of individuals, which are released from the parent at a small size. The chain of salps is the aggregate portion of the life cycle. The aggregate individuals are also known as blastozooids; they remain attached together while swimming and feeding, and each individual grows in size. Each blastozooid in the chain reproduces sexually (the blastozooids are sequential hermaphrodites, first maturing as females, and are fertilized by male gametes produced by older chains), with a growing embryo oozoid attached to the body wall of the parent. The growing oozoids are eventually released from the parent blastozooids, then they continue to feed and grow as the solitary asexual phase, thus closing the life cycle of salps.

The alternation of generations allows for a fast generation time, with both solitary individuals and aggregate chains living and feeding together in the sea. When phytoplankton is abundant, this rapid reproduction leads to fairly short-lived blooms of salps, which eventually filter out most of the phytoplankton. The bloom ends when there is no longer enough food to sustain the enormous population of salps.

Sinking fecal pellets and bodies of salps carry carbon to the sea floor, and salps are abundant enough to have an effect on the ocean's biological pump. Consequently, large changes in their abundance or distribution may alter the ocean's carbon cycle, and potentially play a role in climate change.