Epidermis

Definition

The epidermis is the outermost layer of cells covering an organism's body. In animals, it serves as a protective barrier against environmental factors and pathogens.

5 Must Know Facts For Your Next Test

1. In sponges, the epidermis is made up of pinacocytes that cover the outer surface.
2. The epidermis in cnidarians contains specialized cells called cnidocytes, which are used for defense and capturing prey.
3. Epidermal cells in cnidarians can produce mucus to protect their delicate tissues.
4. The epidermis plays a crucial role in gas exchange for sponges, allowing oxygen to diffuse directly into their cells.
5. Unlike more complex animals, sponges do not have multiple layers of skin; their epidermis is a single layer of cells.

Review Questions

• What type of cells make up the epidermis in sponges?
• How do cnidarians use their epidermal cells for defense?
• What function does the epidermis serve in gas exchange for sponges?

Related terms

Cnidocyte: Specialized cell in cnidarians that contains a stinging organelle used for prey capture and defense.

Pinacocyte: Flattened cell that forms the outermost layer of a sponge's body.

Mucus Secretion: A protective mechanism by which certain animals produce mucus to shield their tissues from harm or desiccation.