"Mammals" PPT courseware on the main groups of animals

Description

"Mammals" PPT courseware on the main groups of animals

【Thinking Activation】

"Bats fly in the sky, moles hide in the ground, whales swim in the sea, and tigers live in the mountains." These animals have different shapes and living environments. Why are they all mammals?

1. Main characteristics of mammals

1. Morphological structure and physiological characteristics:

(1) Body surface: Most body surfaces _____ and have _____ functions.

(2) Body temperature: Body temperature is constant and belongs to _________.

(3) Reproductive development.

①Viviparous: The embryos of most mammals develop in the body of _____, obtain _____ from the mother through _____, and are born from the mother after reaching a certain stage of development.

② Lactation: The female uses her own _____ to nurse her offspring.

③Meaning: Viviparous birth and lactation improve the _______ of offspring.

2. The relationship between mammals and human life

1. Beneficial:

(1) As food: the main source of _________.

(2) Role in the ecosystem: maintaining the _____ of the ecosystem.

(3) Economic value: _____ of some mammals, such as mink skin, Tibetan antelope skin, etc.

(4) Other uses: guide dogs, _____, military horses, etc.

2. Harmful:

For example, rampant rodents can cause harm to agriculture, forestry, and animal husbandry, and sometimes ________.

【Key Points】

1. Mammalian teeth:

(1) Differentiation type.

① Herbivores: differentiated into incisors and molars.

② Carnivores: differentiated into incisors, canines and molars.

(2) Function.

① Incisor teeth: cut off food.

②Canine teeth: tear apart meat.

③Molar teeth: grind food.

(3) The differentiation of teeth is adapted to the animal’s feeding habits.

2. Reproductive development methods of mammals:

(1) Mistaken points: Viviparous birth and lactation are unique reproductive and development methods of mammals, but not all mammals have this feature.

(2) For example: The platypus, one of the most primitive mammals, has an oviparous reproductive mode and can breastfeed, but has mammary glands but no nipples; although the kangaroo is viviparous, it does not have a placenta, and the embryo cannot fully develop in the mother's body.

[Explore and improve]

1. Whales live in the water and look like fish, but they are mammals. Why is this?

Tip: The characteristics of fish are that their body surface is often covered with scales, they breathe through gills, and their reproductive mode is oviparous. Whales have the characteristics of viviparous suckling, a diaphragm in the body cavity, breathing with lungs, and constant body temperature. These are the main characteristics of mammals.

2. When domestic rabbits hear the footsteps of the breeder, they will actively come forward to ask for food, but will be scared away when strangers approach. What structure does this have to do with?

Tip: This is related to its developed brain and nerves throughout the body, which can form complex reflexes to the keeper’s footsteps.

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For more information about the "Main Groups of Animals Mammals" PPT courseware, please click the "Main Groups of Animals ppt Mammals ppt" tag.

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"Mammals" Main groups of animals PPT courseware 5:

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"Mammals" Main groups of animals PPT courseware 4:

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Update Time: 2024-11-25

This template belongs to biology courseware People's Education Edition Biology for Grade 8, Volume 1 industry PPT template

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