Miniature Lives Magnified

About the Digital Collections Programme

The Museum is on a mission to digitise the 80 million specimens in its collection. We want to make the information the specimens hold about the natural world more openly available to scientists and the public.

We have imaged more than 70,000 microscope slides of lice from the Museum's collection. We have been asking digital volunteers for the Museum to help transcribe information from the specimen labels so that the data can be used for scientific research. All of the data that you help us to capture from the labels will be published to our open data portal at data.nhm.ac.uk

About the Louse Slide Collection

Few insect species have colonised the ocean despite their success on land. This is possibly due to crustaceans filling much of the niche for this in the sea. It has also been suggested that how insects breath is not well suited to the high under-water pressure of a marine environment. However some insects such as lice manage to survive underwater at great depths and during long immersion periods.

Lice are permanent ectoparasites, meaning they live on the outside of their bird and mammal hosts. They are highly host specific, with the majority of the ~5,000 louse species being unique to a particular host species. Sucking lice (Anoplura) from the family Echinophtiriidae infest pinnipeds - which are marine mammals such as sea lions, walruses and seals. Scientists who study how animals have evolved think that the pinnipeds may have descended from meat-eating mammals on land (central carnivores). The ancestral pinnipeds therefore probably harboured sucking lice before they ventured into the marine environment, and the two species evolved from there together. That is what makes the parasitic lice and their hosts so interesting for studying co-evolutionary processes.

For example, some pinnipeds can remain at a depth of 1500m for over two hours. This means that lice on these mammals are submitted to massive hydrostatic pressure. Pinnipeds also spend periods of weeks to months submerged in the open ocean, meaning that their lice need to be able to survive cold temperatures and low oxygen environments.

There are thirteen known species of Echinophthiriidae, of which ten are represented in this collection.

About the Echinophtiriidae

There are a number of features that make the lice of the open oceans different from other other lice species, and are central to how they have evolved alongside the pinnipeds to live in a marine environment:

• Their bodies are often more swollen and spherical than other sucking lice (Anoplura).
• They have eye-less, conical heads and do not respond to light.
• Most have shorter, slender front legs and are equipped with different claws than the middle and back stronger bigger legs.
• Some have scales on their abdomen which can trap air bubbles around the body
• They lay large eggs in comparison to louse size and have a very strong glueing substance to attach to hair.
• Arctic species have spines that are used to fix a layer of the seal sebum to the louse to offer waterproofing and insulation to protection against low temperatures.
• They have three nymph stages - first unable to tolerate emersion in water - but all others can.

Echinophtiriidae behavioural adaptations
This family of lice also behave in a different way to other species of lice:

• They do not lay eggs at sea. Reproduction is aligned with the reproduction cycle of their host, such that it only happens when seals are on land. To make the most of this, the female can lay up to 8 eggs a day.
• Transmission of lice is almost impossible at sea and most likely to occur on land. Transmission is suggested to occur between bulls and cows, breeding cows to pups and pups to pups.
• The major path of transmission is from nursing cow to pup within six hours of birth - this mass movement is considered to be in response to the ‘favoured’ factor of temperature. The difference in temperature and(pelage) are thought to influence how lice move between seals. Pups have a mean temp of 34 degrees and the mother has a mean temperature of 28.4. Underhairs of the pup are also thinly distributed and less dense than adults meaning that lice are more likely to penetrate the skin and access blood. (Wigglesworth, 1941)
• The pups have a softer longer coat from birth up to 2-3 weeks which is not waterproof and the pup does not swim. During this stage the lice lay eggs and develop through the first instar nymph stages. These stages cannot survive the water and so taking place on the pup that doesn’t swim allows an ideal opportunity for development. Pups in their first three weeks have 3x the amount of lice as all other stages of seal development. (Dubani, 1955)
• They can feed less often than other species of Anoplura, but a blood meal needed at least once a week to sustain the lice.
• Often clustered around body parts that are warmer/ receive more blood flow at sea eg Skin temp on flipper rises more frequently on hind flippers after diving.