Erinaceus

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Erinaceus is a genus of hedgehogs in the Erinaceidae family. There are four main species: Erinaceus europaeus (the European hedgehog), E. amurensis, E. concolor, and E. roumanicus. They live across Europe, the Middle East, parts of Russia, and reach northern China and Korea. The European hedgehog has been introduced to New Zealand.

Appearance and anatomy
- Hedgehogs in this genus have spines made of keratin. The spines are hollow with air gaps to keep them light. Spines taper to a point and are attached to the skin with a bulb at the base. Small muscles can raise the spines when needed.
- They are about 20–30 cm long and weigh 400–1200 g.

Lifestyle
- They are nocturnal and seek shelter in shrubs or burrows during the day.
- The common defense is to roll into a ball with spines facing outward. Loose skin at the back helps wrap the body like a drawn string.
- They are mostly solitary, except during breeding season.
- Some hedgehogs self-anoint, producing foamy saliva on their spines. The purpose is not fully understood; it may be for defense or mating.

Reproduction and life cycle
- Mating is often polygynous.
- After fertilization, gestation lasts 30–40 days.
- Young are born blind and hairless, with 2–5 babies on average (up to 10).
- Spines form within a few weeks. Weaning occurs at 4–6 weeks.
- Sexual maturity is reached around 12 months.
- In the wild, they live about 2–5 years; in captivity, up to around 10 years.

Diet and biology
- Erinaceus hedgehogs are omnivores: they eat small invertebrates, small vertebrates, fruits, vegetables, and fungi. They can even eat venomous snakes or toxic beetles.
- Some species show resistance to snake venom, much more than typical lab animals.