Salps are often mistaken for jellyfish, but these common gelatinous marine organisms are entirely harmless to humans. These clear, barrel-shaped creatures drift in the open ocean and are frequently encountered by swimmers and divers worldwide. The answer to whether a salp can sting is an absolute no, a fact rooted in their distinct biological makeup.
The Direct Answer: Salps Are Harmless
Salps lack the specialized biological structures necessary to deliver a sting. The stinging sensation commonly associated with gelatinous sea life comes from nematocysts, which are tiny, harpoon-like stinging cells found exclusively in the phylum Cnidaria. This phylum includes true jellyfish, sea anemones, and corals. Salps belong to a completely different phylum and do not possess any form of these stinging cells.
Physical contact with a salp poses no threat because their bodies are a transparent, gelatinous tunic. Any sensation felt upon touching a salp is likely due to the sticky nature of their mucous feeding net or irritation from other microscopic organisms present. Swimmers who report a stinging feeling after encountering a mass of salps have most likely encountered a true, small jellyfish or another stinging organism mixed in with the salp bloom.
What Exactly Is a Salp?
A salp is a type of pelagic tunicate, a free-swimming marine invertebrate classified in the subphylum Tunicata. Taxonomically, salps are part of the phylum Chordata, the same group that contains all vertebrates, including humans. This makes them more closely related to humans than they are to jellyfish. The adult salp is a semi-transparent, barrel-shaped organism, typically ranging from a few millimeters to 10 centimeters long.
Movement is achieved through jet propulsion, where the salp contracts bands of muscles ringing its body to pump water in through one opening and out the other. This process simultaneously serves their feeding function, as the water passes through an internal mucous net that strains out microscopic phytoplankton and bacteria. This filter feeding earns them the nickname “the ocean’s vacuum cleaner” because they can filter over 1,000 times their body volume per hour.
Why Salps Are Confused With Jellyfish
The primary reason salps are mistaken for jellyfish is their physical similarity. Both are gelatinous zooplankton, meaning their bodies are mostly water and lack hard parts, giving them a clear, translucent appearance. This visual likeness leads many people to assume they share the same stinging defense mechanism as true jellyfish.
Salps frequently appear in massive numbers, which contributes to the confusion and fear of a large swarm. They often form dense blooms, and individual organisms can link together in chains or clusters that sometimes stretch for several meters. When these chains wash ashore, they create a thick, mucous-like deposit that is easily misidentified as the remains of a deadly bloom of stinging animals.
Unique Life Cycle and Ecological Role
Salps exhibit a complex reproductive strategy known as the alternation of generations, cycling between two distinct forms. The solitary form, called the oozooid, reproduces asexually by budding off a chain of identical individuals. These connected individuals form the aggregate, or blastozooid, phase, which is the form that reproduces sexually.
This rapid life cycle allows salps to take advantage of sudden increases in food availability, such as phytoplankton blooms, by multiplying their population quickly. When food is abundant, they are considered one of the fastest-growing multicellular animals, capable of reaching maturity in as little as 48 hours. This ability makes them an important component of the ocean ecosystem.
Salps play a significant role in the ocean’s biological carbon pump, the process that moves carbon from the surface to the deep sea. Their intense filter feeding results in the production of large, dense fecal pellets that are rich in carbon. These pellets sink rapidly, sometimes traveling at rates between 400 and 1,200 meters per day, sequestering carbon in the deep ocean before it can be broken down in surface waters. During a large bloom, salps can export substantial amounts of carbon, increasing the efficiency of the biological pump and influencing global carbon cycles.