Integuement of Fishes

Question 1

What’s the basic structure of skin?

Answer 1

(outside to inside)

• epidermis
• dermis
• hypodermis (not in all vertebrates)

Question 2

What layers can be present in the epidermis and what do they do?

Answer 2

• inner-most layer: stratum germinativum, makes new cells
• outside layer: stratum corneum, keratinized for water proofing
• if middle layer: stratum granulosum, recieves pushed up cells from inside layer
• may also have glands

Question 3

What layers and structures are present in the dermis?

Answer 3

• stratum spongiosum, contains pigment cells, chromatophores
• stratum compactum, contains lots of fibres
• lots of fibres, nerves, blood vessels, connective tissue

Question 4

What does the hypodermis consist of and where is it found if present?

Answer 4

• beneath dermis

- contains fat cells for energy storage and insulation

Question 5

What are some of the different functions of integuement?

Answer 5

• physical barrier for protection
• respiration, excretion
• thermoregulation
• colours, odours, toxins
• locomotion

Question 6

What are some ways integuement can vary across vertebrates?

Answer 6

• # and complexity of glands
• variation in stratum corneum
• bone development in dermis

Question 7

What type of glands are present in fish?

Answer 7

• uni/multicellular mucous glands
• photophores
• poisonous glands

Question 8

What’s the main function of the stratum corneum in the epidermis?

Answer 8

• protection from dessication

- derivatives include scales (not in fish), feathers, hair, claws

Question 9

What is the dermis in fish primarily made out of?

Answer 9

• scales made of bone covered by thin epidermis

- sometimes hard enamel coating

Question 10

What are the different types of scales and what fishes are they found in?

Answer 10

• elasmoid (in teleosts)
• ganoid (in stugeons, paddlefish, gars, bowfin)
• cosmoid (in ancient fish)
• placoid (in sharks and rays)

Question 11

What makes up a placoid scale?

Answer 11

• enamel, dentin, pulp cavity
• protrude through epidermis
• scales oriented posteriorly to reduce drag

Question 12

What makes up ganoid scales?

Answer 12

• ganoine=thick enamel
• no dentin or vascular bone
• thick lamellar bone
• covered by thin epidermis

Question 13

What makes up elasmoid scales?

Answer 13

• thin lamellar bone
• no enamel
• can be modified into plates