[BIO 11.1] E14 - Animal Integuments

• Integuments and Integumentary Derivatives


  • SPECIMEN (INTEGUMENT TYPE -> DERIVATIVES)
  • Ascaris (epidermis -> cuticle)
  • Bird (skin -> plumage, horny scales, talons, beaks)
  • Shrimp (epidermis -> exoskeleton)
  • Earthworm (epidermis -> collagenous cuticle, setae)
  • Fish (skin -> bony scales)
  • Insect (epidermis -> sclerotinous shell, setae)
  • Sea Urchin (skin -> spines)
  • Snail (mantle & epidermis -> shell)
  • Turtle (skin -> carapace, plastron, horny scales, claws, beaks)
  • Frog (skin -> cuticle)
  • Human (skin -> hairs, nails)
• True Horns vs False Horns

  True Horns (Bovids): epidermal origin, unbranched, hollow, permanent, present in both sexes

  False Horns (Cervids): dermal origin, branched, solid, seasonal, present only in males
• Integument


  Outermost covering of the animal
• Integument

  • One or more layers of connective and epithelial tissues
  • For protection, sensation, and homeostasis
• Integument

  • Epidermis
  • Skin
  • Mantle
• Integumentary Derivatives

  • Long-lasting secretions and deposits of the epithelium
  • May be flat, membranous, or elaborate in structure
  • Many derivatives are shed off or replaced in the life of an animal
• Hardened integumentary derivatives form an exoskeleton
• Invertebrates

  • Integument consists of an epithelial layer: the epidermis
  • Can secrete substances for protection and to prevent desiccation
• Shell and Bivalves

  • Calcareous
  • Mantle underneath
  • Two layers of epithelial tissue
  • Separated by a layer of connective tissue
• Ascaris

  • Collagenous cuticle
  • Hair-like setae are chitinous
  • Thin, pigmented
  • Longitudinal muscle
• In arthropods, the cuticle is segmented into plates
• Exposed part of the snail: foot (epidermis)
• Stratum Corneum (SC)


  Squamous cells that are dead and constantly being shed off
• Stratum Germinativum (SG)


  Monolayer columnar cells that continuously divide and give rise to new cells that are pushed to the outer layer
• As cells migrate

  1. They become more and more flattened

  2. Differentiate into the keratinized cells of the stratum corneum

  3. Assume cuboidal to spherical shapes and make up a transitional layer between the SC and SG
• Stratum Laxum (SL)


  Layer of loose connective tissue
• Cutaneous glands


  • Formed by the infolding of the SG into the dermis
  • Penetrate the epithelial layers where glands have been sectioned centrally
  • Secretes poison
• Chromatophores


  • Cells that contain darkened pigment granules for coloration, mostly beneath the epidermis
• Stratum Compactum (SCP)


  • Made of dense, irregular connective tissue in alternating vertical and horizontal strands
• Subcutaneous Loose Connective Tissue (SLCT)


  Connects skin with the underlying muscle
• • Dermis
- Connective Tissues
  • Epidermis - Stratified Squamous Epithelium