In this article we will discuss about Lata Fish:- 1. Systematic Position of Lata Fish 2. Habit and Habitat of Lata Fish 3. Geographical Distribution 4. External Structures 5. Digestive System 6. Respiratory System 7. Circulatory System 8. Other Systems.
- Systematic Position of Lata Fish
- Habit and Habitat of Lata Fish
- Geographical Distribution of Lata Fish
- External Structures of Lata Fish
- Digestive System of Lata Fish
- Respiratory System of Lata Fish
- Circulatory System of Lata Fish
- Other Systems of Lata Fish
1. Systematic Position of Lata Fish:
The lata fish (Ophiocephalus or Channa) punctatus is the commonest bony fish used in the practical classes in different colleges of West Bengal and other provinces of India’. These fishes are commonly called snake- headed fishes because the head resembles superficially that of snakes. The anatomy of Lata is incompletely known. It is typically constructed on the basic teleostean plan.
However, the following description will be helpful in the practical work:
Subphylum: Vertebrata (= Craniata)
Order: Ophiocephaliformes (= Channiformes)
Family: Ophiocephalidae (= Channidae)
Scientific Name [Channa punctatus]
Bengali: Lata, Taki
Oriya: Gurrie, Gorissa
Telegu: Mitta, Currumeenu, Mattagidasa, Muttah
Tamil: Pottai, Korava, Para-korava
Kanara: Kuchi, Korava
Gujarati: Kadwa, Soap, Daku, Murrel
2. Habit and Habitat of Lata Fish:
The lata fish inhabits fresh-water ponds and ditches. It is usually carnivorous and eats other small fishes and small aquatic animals. Lata fish is notable for migration overland from one bond to another during- rains. The ability to breathe in air by its accessory respiratory organ helps the fish to thrive well out of water for a considerable period of time.
3. Geographical Distribution of Lata Fish:
It is found throughout the plains of India, Pakistan and Bangladesh.
4. External Structures of Lata Fish:
The body of lata is elongated (Fig. 6.29) and covered with ctenoid scales (Fig. 6.30B). It has been recorded that cycloid scales are also present (Fig. 6.30A). The body is divided into head, trunk and tail regions. The head is depressed and covered by large plate-like scales resembling the ‘head shields’ of snakes. The eyes are placed on the lateral sides of the head.
The dorsal fin is single. The anal fin is also extensive and extends from the posterior end of the anus. Both the dorsal and anal fins are undivided and are supported by spinous bony fin-rays. The caudal fin is of homocercal type. The lateral line is interrupted at places.
5. Digestive System of Lata Fish:
The mouth is bounded by upper and lower jaws. The jaws are provided with sharp conical teeth. The buccal cavity is spacious and leads into a short tubular oesophagus. The stomach is an elongated sac-like structure.
The most important feature to note in the digestive system of Lata is the presence of only two pyloric caeca (Fig. 6.31). These caeca open at the junction of the intestine and the pyloric end of the stomach. The intestine is a coiled tube with its distal part dilated as rectum. The anus is located on the ventral surface and in front of the anal fin.
The liver is a distinct bilobed glandular structure. The bile produced in the liver is stored in the gall-bladder situated on the ventral side of the right lobe of liver. The bile duct opens into the intestine just near the point of origin of the pyloric caeca.
6. Respiratory System of Lata Fish:
The primary respiratory organs are four pairs of gills, two pairs on either side. The gills are placed in the gill-chamber and the gill- openings are wide. The structure of the gills is similar to that of Rohu. The lata fish is capable of living in absence of water for a considerable period of time.
When out of water, this fish is able to breathe air by a pair of specialised supra-branchial cavities. The supra-branchial cavities are situated in the gill-chambers. These are lined internally by a highly vascular membrane that physiologically functions as lungs. These are accessory respiratory structures.
7. Circulatory System of Lata Fish:
The circulatory system is built on teleostean plan. The heart is composed of a thin-walled sinus venosus, an oval muscular ventricle and an auricle. The conus arteriosus is absent and this region, like that of Bhetki, is marked by the presence of a pair of valves guarding the entrance of the bulbus aorta.
The bulbus aorta is non-contractile and represents the dilated base of the ventral aorta. The bulbus aorta and the ventral aorta are covered by a tough membrane.
Afferent branchial system:
The deoxygenated blood from the ventricular cavity is conveyed through a stout median ventral aorta to the gills for aeration by four pairs of afferent branchial arteries (Fig. 6.32). All the four pairs of the afferent branchial arteries have independent origin from the ventral aorta.
The first and second pairs of the afferent branchial arteries are simple straight arteries leading from the ventral aorta to the corresponding pairs of gills. While the third and fourth afferent branchial arteries of each side cross each other forming a loop after their origin from the ventral aorta (Fig. 6.32).
Efferent branchial system:
The efferent branchial arterial system is peculiar. The first and second pairs of efferent branchial arteries are lacking (Fig. 6.33). The third efferent branchial artery on each side receives oxygenated blood from the third gill of that side and gives off a cephalic artery.
This artery runs forward and bifurcates into an external carotid artery and an internal carotid artery. A transverse artery acts as a connecting bridge between the third and fourth efferent branchial arteries of the two sides. The left fourth efferent branchial artery gives origin to the dorsal aorta.
The coeliacomesenteric artery originates from the point of union of the transverse artery and the right fourth efferent branchial artery. Two subclavian arteries arise independently on the two sides and each divides into two arteries—the pectoral artery supplying the pectoral fin and a pelvic artery to the pelvic fin.
The dorsal aorta occupies a mid-dorsal position and runs posteriorly up to the tail as caudal artery. Along its course it gives off paired segmental arteries, gonadal arteries and renal arteries.
The absence of first and second pairs of efferent branchial arteries in Lata is difficult to interprete. The oxygenated blood from the first two pairs of the gills is possibly drained into the supra-branchial cavity directly through some sort of capillary networks.
These capillary networks together with that of the supra-branchial cavity unite to form an artery which joins with the cephalic arteries. The venous system is strikingly similar to that of Rohu fish.
8. Other Systems of Lata Fish:
The nervous system, the organs of special sense and the urinogenital system resemble basically that of other bony fishes. Figures 6.34 and 6.35 give an idea of the origin and distribution of V, VII and X cranial nerves in Lata.