Explain the occurrence of thorns in plants and animals.

The emergence of thorns in plants and animals is adaptive. Spines are modified organs of plants – leaves, stems. One of the functions of the spines is the condensation of water vapor. For succulents, this function of thorns is often the main; for some types of cacti with a poorly developed root system, it is the thorns that are the main organ of water supply.
Many functions of thorns are associated with protecting the surface of plants, especially in young plants, from too bright sun rays, as well as from eating animals and other injuries.
Thorns (thorns) on the fruit or on dried leaflets of the inflorescence wrapper (especially in cases where there are hooks at the ends of the thorns) serve for zoohoria – the spread of seeds through animals.
Some cacti have nectar-bearing spines that secrete nectar to attract pollinators.
For animals, thorns are a protection against predators. Spines are derivatives of the epidermis, fins in fish. For example, moloch lizard, hedgehog, echidna, some fish, etc.

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