Literature Review
For this week’s post,
the focus of the discussion will be on several features that was mentioned in
the previous post and more in-depth understanding regarding these features.
Skin
As mentioned in previous post, crocodile has a unique scale
that is different from other reptiles. This bony scale layer is known as scute
and can be found along the crocodile’s back. Different from the scale found on
snakes or lizards, scutes are formed in the lower vascular layer of the skin
and the epidermal element is only the top layer. Underneath the epidermal
element lies the osteoderms layer. Osteoderms are bony deposits forming scales
and in many case, functions as defensive armor. In crocodile, osteoderms also
functions as heat exchangers, allowing these large reptiles to cool down or
heat up rapidly.
The scute layer helps prevent water loss which allows
crocodile to stay on the land for longer period of time. This is due to the
structure of the scute, which is made up of keratin, an insoluble protein that
helps waterproof the skin. Keratin can also be found in many other animals, but
the most common example would be human’s hair. Human’s hair is basically made
up of keratin, which is why it is waterproof.
Scales/ Bumps on
crocodile’s face
The scales found on the face or covering the head of the
crocodile can be seen different from the scale on the rest of the body as it is
relatively thinner. Tiny bumps as shown in figure below can be seen and these
bumps are sensory pits or integumentary sensory organs (ISO). These ISOs helps
crocodile gather information about the surrounding and ISOs as a sensory organ
can function for water disturbance detection (track prey or avoid predator),
mating, reproduction and osmo-regulation. ISO’s structure is made up of many
nerves and tissues as well as mechanoreceptors that allows for sensitivity to
vibration and pressure. This helps crocodile to detect vibration underwater
when there are movement nearby which allows them to both hunt prey and escape
from predator. These sensory organs are capable of vibration detection of up to
35Hz and have a response time of less than 100 milliseconds.
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