Crabs vs. Lice

What's the Difference?

Crabs and lice are both types of parasites that infest the bodies of their hosts, but they differ in their appearance and preferred habitats. Crabs, also known as pubic lice, are small insects that infest the pubic hair, causing intense itching and discomfort. They have a crab-like appearance with a round body and large claws, which they use to cling onto hair shafts. On the other hand, lice are tiny insects that infest the scalp, causing itching and irritation. They have a more elongated body shape and six legs, which they use to crawl and attach themselves to hair strands. While both parasites can be a nuisance, crabs are typically transmitted through sexual contact, while lice can be spread through close personal contact or sharing personal items like combs or hats.


Photo by Mae Mu on Unsplash
SizeVaries (up to 4 inches)Very small (less than 0.1 inch)
Body ShapeRound and compactFlat and elongated
Number of Legs106
HabitatMarine and freshwaterPrimarily on mammals
FeedingScavengers, predatorsParasitic
HostsCrustaceans, fish, mammalsMammals, birds
TransmissionDirect contact, sexual contactDirect contact, sharing personal items
DiseasesNone (except for pubic lice)Can transmit diseases
Photo by Nathachai Thongniran on Unsplash

Further Detail


Crabs and lice are both small creatures that belong to the arthropod family. While they may share some similarities, they also have distinct differences in terms of appearance, habitat, behavior, and impact on humans. In this article, we will explore these attributes in detail, shedding light on the unique characteristics of both crabs and lice.


Crabs are crustaceans with a hard exoskeleton, typically featuring a broad carapace, a segmented body, and ten legs. Their front pair of legs is modified into claws, which they use for defense and capturing prey. Crabs come in various sizes, shapes, and colors, ranging from the tiny pea crab to the massive Japanese spider crab.

Lice, on the other hand, are small insects that are usually wingless and have flattened bodies. They have six legs, each ending with a claw-like structure that allows them to cling to hair or feathers. Lice are typically much smaller than crabs, with adult lice measuring only a few millimeters in length.


Crabs are predominantly aquatic creatures, inhabiting both saltwater and freshwater environments. They can be found in oceans, seas, rivers, lakes, and even on land near water bodies. Some species of crabs are adapted to live in burrows or on sandy beaches, while others dwell in coral reefs or rocky areas. Their ability to adapt to various habitats is remarkable.

Lice, on the other hand, are primarily parasitic insects that live on the bodies of mammals or birds. They are highly specialized to their hosts and are usually found in specific areas such as the scalp, body hair, or feathers. Lice require the warmth and protection provided by their hosts to survive and reproduce.


Crabs are known for their diverse behaviors. Some species are solitary, while others live in large groups or colonies. They exhibit various feeding habits, including scavenging, filter-feeding, and predation. Crabs are also known for their ability to regenerate lost limbs, a unique trait among arthropods. Additionally, many crab species have complex courtship rituals and engage in elaborate displays to attract mates.

Lice, on the other hand, have a more limited behavioral repertoire. They spend most of their lives clinging to their hosts, feeding on blood or skin cells. Lice reproduce by laying eggs, known as nits, which attach firmly to hair or feathers. They rely on direct contact between hosts for transmission and cannot survive for long periods away from their hosts.

Impact on Humans

Crabs are generally not harmful to humans, except for a few species that possess powerful claws and can deliver painful pinches. However, crabs are highly valued in culinary traditions worldwide and are a popular seafood delicacy. They are harvested for their meat, which is rich in protein and low in fat. Crabs also play a crucial role in marine ecosystems as scavengers and predators, contributing to the balance of marine life.

Lice, on the other hand, can have a significant impact on humans. Head lice, for example, are a common problem, especially among children. They cause itching and discomfort and can lead to secondary infections if left untreated. Body lice, on the other hand, are associated with poor hygiene and can transmit diseases such as typhus. While lice infestations can be challenging to eradicate, they are generally not life-threatening and can be effectively treated with appropriate medications.


In conclusion, while crabs and lice are both arthropods, they differ significantly in terms of appearance, habitat, behavior, and impact on humans. Crabs are aquatic creatures with a hard exoskeleton, while lice are small insects that live on the bodies of mammals or birds. Crabs exhibit diverse behaviors and have a positive impact on marine ecosystems, while lice have a more limited behavioral repertoire and can cause discomfort and health issues in humans. Understanding these attributes helps us appreciate the unique characteristics of both crabs and lice and their respective roles in the natural world.

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