Marine Mammal Parasite of the Month- November 2021
This parasite is an insect from the suborder Anoplura, which consists of sucking lice. Like other insects, they have antennae, a thorax, an abdomen, and legs. Unlike other insects, they have no eyes, and their mouth contains 2 rows of 4 large hooks. Their thorax is shaped like a trapezoid and covered in long hairs and spiracles. Their abdomen is covered in oval scales in a pattern, although first stage nymphs (newborn lice) lack this characteristic. They are identifiable by these scales and the vertical grooves in the spines that line their abdomen. These spines are likely used for sensing and possibly holding the host’s sebum to protect itself from low temperatures. For those that don’t know, sebum is an oily substance that forms a protective coating on the surface of the skin. They also use their smaller forelegs for sensing. In general, females are larger and rounder while males have a pointed abdomen. Being from the family Echinophthiriidae, the only sucking lice family to inhabit semi-aquatic animals, this parasite has special adaptations that allows it to survive in the ocean for periods of time. For instance, it uses oxygen in seawater and reduces its metabolic activity to survive long periods underwater. Additionally, the tibia-tarsus segment of their second and third pairs of legs are strengthened to hold onto the hair of the host in a turbulent water environment. The abdomen is membranous for better gas exchange underwater and because of the lack of rigid plates in their body, they can withstand high pressures. Remember the scales we mentioned earlier? Well, they have a cool trick where they can close these scales to keep air in and water out when the louse is submerged in water and may also protect the louse from low temperatures. What is this parasite and what animals do you think it likes to live on?
Posted by fall intern, Adrienne V-H.