听力音频：

• Some nocturnal animals lose certain 31 ______ over time due to lack of necessity.

• They have a varied 32 ______ compared to their three-toed relatives because they face less competition at night.
• Their flexible 33 ______ allows them to scan their surroundings efficiently.
• These sloths adjust their 34 ______ depending on environmental conditions.
• The presence of algae in their 35 ______ helps them blend into their environment.

• North Island brown kiwis adapted to a nocturnal lifestyle to escape 36 ______.
• Their eyesight lacks the ability to perceive 37 ______ but they have an excellent sense of smell.
• The 38 ______ laid by kiwis are unusually larger in proportion to their size.
• Bats have specialized 39 ______ skin for echolocation.
• Bats rely on 40 ______ to keep their claws secure while sleeping.