What Color Are Crabs? Exploring the Diverse Hues of Crustaceans

Common crab colors

• Blue-green: The Atlantic blue crab has a blue-green shell with a white underbelly. Males have blue-tipped claws, while females have red-tipped claws

• Red: Many crab species turn red when cooked, but some species naturally have reddish hues in the wild

• Brown: Various crab species exhibit brown coloration as camouflage in their natural habitats

• White: Some crabs have white or light-colored undersides, which can help with camouflage when viewed from below in water

Factors influencing crab color

• Species: Different crab species have evolved distinct colorations suited to their environments and survival needs

• Environment: Some crabs can change their color to blend in with their surroundings, reducing conspicuousness

• Age and maturity: The color of a crab may change as it grows and matures

• Diet: A crab's diet can influence its shell color, especially in younger crabs

Color vision in crabs

• Visual capabilities: Some crab species, like the crab spider Misumena vatia, have at least two types of photoreceptors, suggesting color vision capabilities

• Eye structure: The eyes of some crab species have a broad superposition of the visual field between different eyes, supporting the integration of visual information

• Retina organization: In some species, the mobile retina of the principal eyes is organized in three layers of different types of rhabdoms, which may contribute to color perception

Color changes in hermit crabs

• Shell selection: Hermit crabs change shells frequently, which can affect their conspicuousness against different backgrounds

• Behavioral adaptation: Hermit crabs adjust their startle responses based on their level of conspicuousness, suggesting awareness of their current coloration

• Predation threat: Some hermit crabs exhibit reduced crypticity (increased conspicuousness) when the threat of predation is high