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Key to skulls of British Insectivores |  |
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Insectivores have continuous rows of similar, pointed teeth, considered
by taxonomists to be a primitive feature. There are eight British insectivores, three of
which only occur in the Channel Islands. The hedgehog is much larger than the others : | |||
| 1. | a) | Overall length greater than 40mm. | HEDGEHOG |
| b) | Overall length less than 40mm. | 2 | |
| x | |||
| 2. | a) | Overall length close to 35mm, prominent canine teeth, with zygomatic arch. | MOLE |
| b) | Overall length much less than 35mm, front pair of teeth much larger than the rest, no zygomatic arch. | 3 | |
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The remaining insectivores are shrews. Their skulls are very small and
fragile, but shrew jaws are easily recognised. A powerful handlens or low-power microscope is necessary for the identification of shrew skulls. | |||
| 3. | a) | Teeth pigmented (red tipped). | 4 |
| b) | Teeth not pigmented (Channel Islands only). | White-Tooth SHREW 2sp | |
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Front upper teeth of Common Shrew, Sorex araneus. 1 - 5) Upper single-pointed teeth. F) First upper tooth. |
| 4. | a) | Upper surface of first lower tooth smooth, four upper single-pointed teeth. | WATER SHREW |
| b) | Upper surface of first lower tooth wavy, five upper single-pointed teeth. | 5 | |
| x | |||
| 5. | a) | Upper tooth row less than 7mm, third upper single-pointed tooth larger than second. | PYGMY SHREW |
| b) | Upper tooth row longer than 7mm, third upper single-pointed tooth smaller than second. | COMMON SHREW | |
| The French Shrew, Sorex coronatus is very similar to the Common Shrew. Its British distribution is confined to Jersey. | |||