Geographical distribution : Erinaceus is found in northern hemisphere, West Indies, Africa and India. Cretaceous to Recent.
Habit and habitat: It inhabits holes and bushes during day and it comes out during night to feed. It is omnivorous, feeding on fruits, roots, insects, worms, slugs and other small animals. Hedgehog hibernates during winter. When alarmed or disturbed, it has the habit of rolling its body like a spiny rounded ball.
Comments:
1. Commonly called a hedgehog.
2. Animal characterized by the presence of sharp backwardly directed spines on
the dorsal side, while the ventral side has soft fur. Body elevated above ground and divided into head, neck, back and abdomen.
3. Head conical and produced into small snout bearing nostrils at the tip.
4. Mouth small bearing 36 sharp pointed teeth.
5. Eyes small. Pinnae and legs short. No marsupial bone or pouch. Number of ribs 14-15.
6. Hind and forelimbs short.
7. A muscle band is found over the neck and sides to move spines.
8. Vagina single, foetus develops within the uterus of a female, attached by placenta.
Special features : These are probably the most primitive of the Eutherians. The brain represents a low grade of organization. Cranial cavity is small. The stomach is simple. The allantoic placenta is discoidal and deciduate but there is provisional yolk sac placenta. Many young people are born at a time. When distributed hairs of dorsal surface become converted into spines and due to strong development of dermal muscles. The animal rolls into a spiny rounded ball.
Source:
1. Practical Zoology Vertebrates by S.S.Lal. 2. A Manual of Practical Zoology Chordates by Dr. P.S. Verma.
