A recent video captured by the Schmidt Ocean Institute showcases a rattail fish, belonging to the genus Macrourus, filmed at a depth of 1,604 feet near the South Sandwich Islands in the South Atlantic Ocean.

In this footage, the fish is seen hosting two grotesque bloodsucking copepod parasites, Lophoura szidati, which resemble pig tails due to their long egg sacs.

These copepods are classified as mesoparasites, partially embedding themselves in the fish's flesh and feeding on its muscle tissue by scraping it.

While the life cycle and lifespan of L. szidati remain largely unknown, it is believed that they can stay attached to their host for several months, even leaving remnants after death.

James Bernot, an evolutionary biologist, notes that remnants of the parasites' embedded heads can linger in their host for many years, highlighting their long-term impact.

L. szidati females carry sacs containing hundreds of developing eggs, showcasing a high maternal investment as they nurture their offspring until they hatch into swimming larvae.

The bizarre appearance of the egg sacs, which contain hundreds of eggs, contrasts sharply with the parasites' predatory nature.

The copepods likely attach to their hosts during their larval stage, marking the beginning of their transformation into mature parasites.

Observations of deep-sea parasitism in Antarctic waters are rare, and L. szidati is among the most common parasites found on Macrourus species.

This discovery contributes to a greater understanding of parasitic life in deep Antarctic waters, emphasizing the ecological roles of even the smallest marine organisms.

Rattail fish, commonly known as grenadiers, inhabit cold waters across the Atlantic and Southern Oceans at depths ranging from 1,312 to 10,450 feet.

Despite limited knowledge about deep-sea fish parasites, L. szidati stands out as one of the most prevalent parasites affecting Macrourus species in the region.