A Thousand Tiny Tunicates

A Single Salp

There are several transparent and translucent organisms that dwell in the ocean. This transparency helps them blend in with the surroundings and hide from predators. Some are too inconspicuous to be noticed when alone, like the tunicates, Salps. Though they are quite abundantly found in oceans, not many people know about these tiny, transparent creatures. They have small, crystal clear, sac-like bodies with openings at both ends. Though they resemble jellyfish, these salps are actually ancestors of vertebrates, like fish, and even have a heart, gills and a vascular system. In the larval form, they have a primitive backbone, eye and a hollow brain.  They contract their sac-like bodies, taking in water through one end and expelling it out the other. This water, before being dismissed from their bodies, is filtered for food like phytoplankton. Sometimes these salps travel and feed alone and sometimes they form huge colonies by linking themselves to other Salps. Each salp, depending on the species, can grow up to a length of a few inches but Salp colonies can extend up to fifteen feet in length. Some species even exhibit bioluminescence and their colonies appear like long, glowing chains in the oceans. Large salp colonies indicate to fishermen, the presence of Pomfret and Herring as these prized fish feed on them. Salps are significantly more abundant where there are phytoplankton blooms. Large colonies voraciously devour the copious amounts of phytoplankton. The salps even bud off clones of themselves to partake in the feast. They are believed to be the fastest growing multicellular organism because of their ability to clone themselves. Since Salps are filter feeders, they feed on even the tiniest diatoms and protozoa. Scientists find it hard to trap such minute organisms to study. So now biologists catch salps and study the contents of their stomach instead, to get to the microscpoic creatures. These tiny salps are used to catch even smaller organisms. Salps, though small, have a major impact on the ocean’s carbon cycle. When salps die after a bloom, billions of their bodies, along with their faecal pellets, carry colossal amounts of carbon to the ocean floor. So these inconspicuous, unfamiliar, tiny creatures could be affecting a massive global phenomenon like climate change. 

Salp Colony