PRACTICAL NOTE ON THE INTERNAL GILL STAGE OF A TADPOLE
PRACTICAL NOTE ON THE INTERNAL GILL STAGE OF A TADPOLE.
Habitat of a tadpole
- Slow-moving water
- Pond
- Freshwater
- stagnant water
Reason for habitat:
- Streamlined body for easy movement (swimming)
- Tail fin for swimming
- Operculum
- Gills for gaseous exchange in water
Features for locomotion
- Long tail with fin for forward propulsion
- Streamlined shape to provide reduced resistance in water
Life Cycle:
- Complete metamorphosis
Stage of specimen in life cycle:
- larva / internal gill stage
Name of preceding stage:
- External gill stage
Name of succeeding stage:
- Limb stage
Features for feeding
- Mouth with horny jaws
- Operculum
- Gills
Method of feeding:
- herbivorous (but not herbivore)
Reasons for the method of feeding:
- Presence of horny jaws
- Presence of a long coiled intestine
Diet:
- pond weed
Feeding habit
- filter feeding
Reasons for the feeding habit
- Presence of gills, which strain food in water
Drawing Details
- Shape: streamlined shape
- Tail longer than half of the entire length
- Shape of the tail muscle
Adaptive features of feeding
- Gill rakers to strain food from water passing over the gills
- The operculum through which water is pushed out
- Long coiled intestine for herbivorous digestion (of water weed)
- Horny jaws for chewing/nibbing water weeds
- The presence of the mouth creates a water flow into the animal.
Locomotory structure in the tadpole
- Tail fin
Adaptations for movement in a tadpole
- Presence of streamlined shape
- Presence of a tail fin to provide propulsion
- The Gill slit opens backward to release water for forward propulsion
Features of biological importance
- Operculum for the protection of gills and ventilation movements
- Mouth with horny jaws for chewing weeds
- Remains of a sucker
- Long tail for swimming in water
- Streamlined body for swimming
Note:
- The tail is made up of a tail fin enclosing tail muscles (note the orientation of the shape of the tail muscles when drawing).
- The tail muscle contracts and relaxes to initiate the movement of the tail fin
- Tail fin is transparent and used for swimming
Observable features in ventral view
- Long Coiled intestine
- Tail muscle
- Remains of Sucker
- Limb bud
- Tail fin
- Anus
Observable features in tadpole (in general)
- Operculum
- Tail fin
- Tail muscle
- Mouth with a horny jaw
- Spiracle
- Anus
- Limb bud
Features of interest in a tadpole
- Long coiled intestine for herbivorous nutrition
- Long tail for swimming in water
- The operculum protects the gills and provides ventilation for gaseous exchange
Part of the tadpole not used at this stage
- The hind limb, because the tail fin is used for swimming
Gaseous exchange in a tadpole
- Water enters by the mouth
- Passes down the pharynx
- Passes over the gills into
- The bronchial chamber
- Formed by the operculum and out by the spiracle
- In the process, Dissolved oxygen diffuses into the blood capillaries in the gills to replace carbon dioxide
Features that adapt the tadpole to live in water
- Streamlined body/shape for easy movement in water
- Tail for swimming
- Gills for gaseous exchange in water.
Locomotory method in a tadpole is Swimming
Reasons:
- Presence of tail fin
- Presence of streamlined shape
Evolutionary features in tadpole
- Tail fin for swimming in water
- Gills for gaseous exchange in water
- The operculum protects the gills
- Single circulation
Similarities between tadpole and bony fish
- Presence of operculum
- Presence of streamlined shape
- Presence of a tail fin
- Presence of tail
- Mouth
- Eyes
- Presence of gills (not external similarities)
Differences between tadpole and bony fish
| Tadpole | Tilapia |
| Absence of scales | Presence of scales |
| Absence of paired fins | Paired fins present |
| Relatively larger tail | Relatively small tail |
| Presence of limb bud | Absence of limb bud |
| Lateral line absent | Lateral line present |
| Absence of fin rays | Presence of fin rays |
| Spiracle present | Spiracle absent |
