Pinkish-brown Salp, Pegea confoederata

Pinkish-brown Salp, Pegea confoederata, Aggregate Form. Collected with a salmon net off the surface about three miles at sea in coastal waters off San Jose del Cabo, Baja California Sur, June 2019.  Length: 12.0 cm (4.7 inches) and travel in a cube that is flattened on the top and bottom. Productive discussions and identification courtesy of Linsey Sala, Scripps Institution of Oceanography, La Jolla, California.

Phylogeny:  The Pinkish-brown Salp, Pegea confoederata (Forskål, 1775), is a member of the Salpidae family of Salps. The genus Pegea is one of three genera in this family, and there are thirteen species in this genus. They are also known as the Spiral Salp. Pinkish-brown Salps, like humans and other complex organisms, are in the Phylum Chordata. This means that they have a notochord (a primitive spine), a dorsal, tubular, nerve chord, a post-anal tail, and pharyngeal slits (filter feeding organs). In many animals, these traits are only present during their embryonic or larval stage of development. For example, in humans the pharyngeal slits are only present during the embryonic stage of development and transition to form the jaw and inner ear structures, the tail disappears completely. In bony fish the Pharyngeal slits transition to form the gill arches. Salp larvae display all of the chordate traits. As they metamorphose, they lose their spine and nervous system.

Morphology:  Adult Pinkish-brown Salps  are essentially sack-like, with two openings (siphons), located at opposite ends of the body. Water flows in one siphon, is filtered through the body, and flows out the other siphon. Contractions of the body wall and cilia move water through the siphons. This water movement is used for respiration, feeding, waste removal, and limited propulsion. The body is cylindrical in shape. Pinkish-brown Salps have a transparent test (gelatinous body covering). Their digestive tract can be seen through the test, appearing as a reddish-orange ball. Pinkish-brown Salps reach 6.0 (2.4 inches) to 12 cm (4.7 inches) in length. They may exist as solitary individuals or as chains of linked individuals. These chains can reach a few meters (~10 feet) in length and are often in a spiral configuration.

Habitat and Distribution: Pinkish-brown Salps are found in open water. They live near the surface and to depths of 182 m (597 feet). While they drift with the current and are considered plankton, they are fairly strong swimmers when migrating between deep and shallow water. Pinkish-brown Salps are found worldwide in tropical and temperate oceans and in Mexican waters are found along along the coasts of both the Atlantic and Pacific Oceans.

Diet: Pinkish-brown Salps are non-selective filter feeders, producing water flow by alternately contracting their oral and anal muscle. They consume microflagellates and diatoms.

Predators:  Pinkish-brown Salps are preyed upon by eaten by sea birds, fish, other plankton, sea turtles and whales.

Reproduction: Pinkish-brown Salps have a complex reproductive cycle that alternates between sexual and asexual generations. A single individual, called an ozooid, reproduces asexually by budding or cloning, 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 lifecycle. Individual salps, in an aggregate chain of individuals, are known as blastozooids. Blastozooids reproduce sexually. The blastozooids are sequential hermaphrodites, first maturing as females and later transitioning to males. Females are fertilized by older males. The growing embryo oozoid attaches to the body wall of the parent. The growing oozoids are eventually released from the parent blastozooids, and then continue to grow in the solitary asexual phase.

Ecosystem Interactions: Pinkish-brown Salps are an important component in the pelagic food web. They provide an important mechanism for energy transfer from primary producers to higher-order consumers and they can also make a significant contribution to biogeochemical cycling in the ocean. Pinkish-brown Salps can grow and reproduce quickly in response to phytoplankton blooms. During these blooms they quickly consume the available food and may then have a massive die-off. These blooms often have significant impacts on other animal species. Additionally, Pinkish-brown Salps are known to host parasitic isopods from the genus Nerocila.        

Human Interactions: Pinkish-brown Salps have a very limited impact on human activities.   From a conservation perspective they have not been evaluated however they common, with a very wide  distribution, and they should be considered to be of Least Concern.

Synonyms: Biphora confoederata, Pegea confederata, Pegea octofora, Salpa (Pegea) confoederata, Salpa confoederata, Salpa dolium, Salpa femoralis, Salpa informis, Salpa octofora, Salpa quadrata, Salpa scutigera, and Salpa vivipara.