Which characteristic is NOT common to all mammals?
They are ectotherms
Their hearts have four chambers
Their skin is covered with hair or fur
Their young are fed with milk produced by organs in the mother’s body

- They are ectotherms

Ectotherms are animals that can't control their body temperature

- Their skin is covered with hair or fur

Marine mammals (whales, dolphins) don't have hair or fur, since that would create drag in the water

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