Question

Задание 1 (30 баллов). Как должен выглядеть ответ на письменное задание по биологии Как устроена раковина моллюсков? Чем питаются моллюски?

Answer 1

Исходно раковина состоит из трёх слоёв: Периостракум — наружный тонкий слой, состоящий исключительно из белка — конхиолина. Фактически, он представлен двумя плотно прилегающими друг к другу слоями. Остракум — средний слой раковины, состоит из кристаллических призм карбоната кальция (СaCO3) в обёртке из конхиолина.

Моллюски всеядны. Водные виды поедают водоросли, мелких животных, падаль. Многие виды отфильтровывают из воды частицы органики. Сухопутные питаются разнообразной растительной пищей.

Answer 2

How is the shell of mollusks structured?

The shell of mollusks is a hard, protective structure that serves as their outer covering. It is composed of calcium carbonate and is secreted by a specialized tissue called the mantle. The shell is made up of two main layers: the outer layer, known as the periostracum, and the inner layer, called the prismatic layer. In some species, there may also be a third layer called the nacreous layer or mother-of-pearl layer.

The periostracum is the outermost layer of the shell and is often thin, organic, and sometimes covered in a layer of protein. It provides protection against physical damage and helps prevent the shell from being dissolved by acidic environments.

The prismatic layer is the middle layer of the shell and is composed of densely packed calcium carbonate crystals. It provides strength and rigidity to the shell.

The nacreous layer is the innermost layer of the shell and is composed of alternating layers of calcium carbonate and an organic matrix. It is responsible for the iridescent appearance seen in some shells and provides additional strength to the shell.

The structure and composition of the shell can vary among different species of mollusks, depending on their habitat and lifestyle. Some mollusks have shells that are thin and fragile, while others have thick and robust shells.