Salp

About Salps

From their clear, blob-like appearance, you’d be forgiven for mistaking the salp for a jellyfish. But it turns out that these gelatinous zooplankton actually are more closely related to humans than to brainless jellyfish. Unlike the jellyfish, salps (and humans) boast complex nervous, circulatory and digestive systems, complete with a brain, heart, and intestines.

Salps use jet propulsion to efficiently glide through the ocean. They’re great at multitasking: while expanding and contracting their muscles to move, they’re also pumping phytoplankton-rich water through their feeding filters, taking in the nutrients they need to survive. 

Salps go through two life phases in which they reproduce asexually, and later sexually, as hermaphrodites. In their asexual stage they produce long chains of identical salps connected together, which then break free and later reproduce sexually, with a baby salp growing up inside each parent in the chain. When food is plentiful, they can quickly create more chains, and each salp can increase rapidly in size. This superpower makes them one of the fastest-growing multicellular animals on Earth. Like all good things, the salp bloom comes to an end when all their available food is consumed.

Found throughout the world ocean, salps play an essential role in the ocean’s biological pump. Because they feed on phytoplankton—which grow in the presence of sunlight and carbon dioxide—salp poop is extremely rich in carbon. When these fecal pellets (and dead salps) fall to the seafloor or are snapped up by other twilight zone creatures, it’s like putting carbon into a bank vault. The carbon remains at the bottom of the ocean for years, if not centuries, helping regulate our climate. Scientists don’t yet have an accurate assessment of how changes in salp numbers and distribution could affect the ocean’s carbon cycle—and impact climate change—but it’s clear that these critters play an important role.