Salps of the Salipidae Family

Cylindrica Salp
Iasis cylindrica

Pinkish-brown Salp
Pegea confoederata

Twin-sailed Salp
Thetys vagina

 

Salps of the Salpidae Family, like humans and other complex organisms, are in the Phylum Chordata. In many animals, these traits are only present during their embryonic or larval stage of development. 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. Salps are in the Subphylum Tunicata, also known as Urochordata. Tunicate larvae are tadpole-like and display all of the Chordate traits. As they metamorphose, they lose their spine, tail, and nervous system. They retain their filter feeding abilities. Adult tunicates are essentially sack-like, with two openings (siphons). Water flows in one siphon, is filtered through the body, and flows out the other siphon. Tunicates maybe sessile or pelagic. Salps and Sea Squirts are also included in this subphylum.

Salps are in the Class Thaliacea. Thaliacea are pelagic tunicates, in which, the two siphons are at opposite ends of the body. 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. This propulsion is primarily used for daily vertical migration. Thaliacea spend the day in deep water and ascend to the surface at night for feeding. Otherwise, they drift with the currents and are considered plankton. Thaliacea have a transparent test (gelatinous body covering). They may be solitary or colonial.

Salps are in the Order Salpida. Salpida have cylindrical, spindle, or prism shaped bodies, often with posterior projections. They have strong muscle bands that do not completely encircle the body. They are capable of forceful contractions in the body wall, giving them fairly strong swimming ability, though they are still planktonic. Salps lack a tailed larval phase. They are characterized by a reproductive cycle that alternates between sexual and asexual generations. They may exist as solitary individuals or as chains of linked individuals. There is only the Salpidae Family in this Order. Salps may reach up to 30 cm (12 inches) in length. They feed on microflagellates and small diatoms that they filter from the ambient water. In turn they are preyed upon by fish, sea birds, sea turtles, whales and other plankton. Salps can grow astonishingly quickly and up to 5% per hour under proper conditions. They can also reproduce quickly, and are known for massive blooms. During these blooms they quickly consume the available food and may then have a massive die-off. These blooms can have significant impacts on their local environments and other animal species as well.

They are found worldwide, primarily in tropical and temperate waters, but they do extend to polar seas. They are found at depths from the surface to 1,500 m (4,920 feet). There are currently 40 known species in the Salpidae Family with the actual number found in Mexican waters poorly documented.