Sea lice are small crustaceans, or copepods, that belong to the Caligidae family. Their order is Siphonostomatoida. It is a species of marine parasite that uses other sea animals as a hosts.
One of the most frequently hosted fish is the wild Atlantic Salmon, and scientists have even had to create drugs to push back against this lice. Due to their interactions with predominantly wild Salmon, they are called Lepeophtheirus salmonis in Latin. They can cause harm to their hosts, especially if a fish develops a sea lice infestation.
Appearance
There is a difference in size between the two genders of sea lice. Females have a far greater genital complex than males. Like many species, the genital complex is the bulk of the body mass. The other sections of the sea louse are the cephalothorax, the leg-bearing segment, and the abdomen. They can produce a large suction cup-like shield that allows them to stick to their hosts efficiently.
Their flattened, oval-shaped bodies, ranging from translucent to light brown or reddish, typically measure a few millimeters to a centimeter in length, making them visible on the skin and fins of their hosts.
Specialized claws on their legs provide a firm grip, while paddle-like swimming legs aid in their planktonic larval stages. Some species possess a protective carapace, and females often carry visible egg sacs. Despite their unappealing name, sea lice exhibit remarkable adaptations for survival in their marine environment.
Did you know…
Sea lice can detect chemical cues released by salmonids, guiding them toward their hosts. This sensory ability is essential for their survival and reproduction. Some species have evolved a hard, shell-like covering called a carapace. This structure provides protection from external threats and the host fish’s immune responses
Habitat
The sea lice have a habitat that is very different from the majority of ocean animals. Instead of spending their time in the open ocean or coral reefs, it use other fish as its habitat.
They are also most common along the coast of Florida and the Caribbean.
It is still unknown how it goes about finding a host in their planktonic stage. The sea louse is suited more to saltwater and targets saltwater fish. However, if they find themselves in freshwater, they can live for around 2-3 weeks and are unable to reproduce. Sea lice are being found in fish farms and can cause a lot of issues for farmers.
Diet
Their diet is extremely simple and is traditionally parasitic. When they have found and attached to a host, they will feed on the fish’s blood and skin tissue for the remainder of their life cycle.
They do not only target Atlantic salmon, having been found on brown trout, Arctic char, and Pacific salmon. It can cause extreme degradation of a host. For example, consistent feeding on mucus, blood, and skin tissue can cause infection of the skin and lesions that can expose the skull.
Reproduction
The reproductive cycle of a sea louse is fairly simple. They are free-swimming before they mature, then spend the rest of their lives attached to a host. Egg strings are developed by female sea lice.
These then hatch and continue their life cycle. The strings contain anywhere from 500 to 1000 eggs. The females can produce 6-11 pairs in 7 months.
Threats
As a parasite, they have a lot of inherent threats. Most of these threats come from human intervention. Their monitoring of salmon farms has started to be conducted. This conscious effort to curb the rise of sea lice has reduced their numbers. This monitoring includes removing dead and infected fish, allowing the healthy fish to thrive in cleaner waters. Several vaccines and drugs have also been used to disinfect the waters, but environmental concerns have limited this avenue.
Their threat to humans is a very convoluted subject. Sea lice are only a threat to fish as they do not host themselves to humans. However, many people get confused with sea anemone or small jellyfish larvae that can get caught in swimmers’ bathing suits and release toxins that cause skin irritation, fever, lesions, nausea, and an itch. This is known as the seabather’s eruption. However, these are completely different animals.
4 More Fantastic Facts about Sea Lice
- The female sea louse is much larger than the males.
- They look for primary salmonids to use as their host.
- They are unable to reproduce in fresh water and can only survive for up to 3 weeks if they are not in salt water.
- Outbreaks of sea bather’s eruption appear to be caused by shifts in South Florida’s currents, with the highest incidence of cases where the Gulf Stream passes closest to shore.
FAQs
Do sea lice attach to humans?
L. Salmonis does not tend to interact with humans due to the fact that it is a fish-based parasite. They sometimes get confused with jellyfish larvae, which can get trapped in swimwear and cause symptoms such as stings, itchiness, and a rash. This is known as the sea bather’s eruption.
Are sea lice dangerous?
Sea lice are dangerous to salmonid species, such as Atlantic salmon, Pacific salmon, brown trout, and Arctic char. They attach to their skin and feed on their blood and tissue. This ultimately impacts negatively on the fish’s health and longevity.
How do sea lice affect salmon?
They affect salmon in different ways. They feed on their blood, mucus, and skin tissue, which causes open wounds. Aggressive feeding can cause a chronic stress response in the fish. They also make the salmon more susceptible to disease due to a reduced immune system and sea lice being carriers.
What happens if you eat a salmon infected by sea lice?
Consuming salmon infected with sea lice generally poses no significant health risks to humans. These are external parasites that primarily affect the skin and fins of fish. They do not typically burrow into the flesh or internal organs, making them unlikely to be present in the parts of the salmon typically consumed.
