Class Pisces: Detailed Comparison of Chondrichthyes and Osteichthyes for NEET Biology
Introduction:
- Class Pisces includes the true fishes.
- They are poikilothermic (cold-blooded) aquatic vertebrates with a two-chambered heart.
- They have streamlined body to cut the water 💦 current.
- They lack the capacity to regulate their body temperature.
- Heart is two-chambered (one auricle and one ventricle).
- Pisces are divided into Chondrichthyes and Osteichthyes.
General Characters of Chondrichthyes :
- They are marine animals with streamlined body and have cartilaginous endoskeleton.
- Mouth is located ventrally. Notochord is persistent throughout life.
- Gill slits are separate and without operculum (gill cover).
- The skin is tough, containing minute placoid scales. Teeth are modified placoid scales which are backwardly directed.
💡NEET IMPORTANT POINT.
📝 Cartilaginous fishes are fascinating marine creatures. Based on the specialized Chondrin protein, their entire endoskeleton is made of cartilage rather than bone..
- Their jaws are very powerful. These animals are predaceous.
- Due to the absence of air bladder, they have to swim constantly to avoid sinking.
- Some of them have electric organs for example Torpedo and some possess poison sting for example Trygon.
- Sexes are separate. In males pelvic fins bear claspers.
- They have internal fertilisation and many of them are viviparous.
🎥 Video Guide: Class Chondrichthyes
Click the timestamps below to watch specific parts of our video lecture:
- 00:00 — Introduction to Class Pisces
- 01:21 — Chondrin Protein & Cartilage
- 03:05 — 2-Chambered Heart Structure
- 05:43 — Ventral Mouth Position
- 06:28 — Placoid Scales & Teeth
- 08:58 — Why Sharks Sink (No Air Bladder)
- 11:11 — Fertilization & Viviparity
- 12:12 — Torpedo (Electric) & Trygon (Poison)
- 13:31 — Important NEET Example
Example of Chondrichthyes :
Scoliodon :
- It is commonly called as Dog 🐕 fish.
- Body of Scoliodon is spindle shape and divided into head trunk and tail.
- Body of scoliodon is dorsoventrally compressed and form snout. It has head , nostril and eyes.
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| Scoliodon |
- Body of Scoliodon has lateral fin which include two pectoral and two pelvic fin.
- It also has an unpaired median fin that include first and second dorsal fin.The tail is heterocercal type.
- Body of scoliodon is covered by the exoskeleton made up of placoid scale which is backward directed.
- Type of Dentition is homodont and polyphyodont.In males Scoliodon,pelvic fins bear claspers.
- They have cloacal between the two pelvic fins.
Pristis
- It is commonly called as Saw fish.It has flattened body with wing like pectoral fins.
- Mouth and gills are located ventrally and eyes are located dorsally .
- It has a long rostral saw which covers 20 to 30% of body length.
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| Pristis |
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- Saw is widest at the base and comprises 20 to 30 long and sharp teeth. Except Saw teeth , it has additional row of teeth.
- It is ovoviviparous and fertilisation is internal.
- It has large triangular pectoral fin on head. It has two dorsal fin found before the pelvic fin.A large caudal fin with distinct lobe is present.
- Body is covered by special scales called dermal denticles.
- According to IUCN, sawfish has been included in endangered species.
Carcharodon
- It is commonly called as Great white shark.It has large bulky body like blunt torpedo.
- It has conical snout with large pectoral fin and dorsal fin with crescent shape tail.
- They are good hunters with strong muscle 💪 with good eye 👁️ sight and strong sense of smell.
- It has complex circulatory system which store heat generated during swimming by muscles.
- White shark are generally solely but some can swim in pairs.
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- Fertilisation is internal. Male insert it's clasper into cloacal of female.
- Reproduction is viviparous because fertilized eggs are retained in body of female for development .
- Body is covered by Placoid tooth shape scal
- Sharks have no swim bladder therefore it keep to swim constantly to avoid sinking.
Trygon
- It is commonly called as Sting ray. It has kite shape flat body. Mouth is ventral and rectangular.
- Tail is whip like and long.It terminate into caudal fin at last.
- Head has no rostellum. Pectoral fin are fused with the head.
- Spiracles are present behind the eyes on dorsal side.
- Five pairs gill slits are present on ventral side for respiration.
- Fertilisation is internal. Male has clasper near pelvic fin and insert into cloacal of female.
- Reproduction is viviparous because fertilized eggs are retained in body of female for development.
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| Trygon |
- Body is covered by Placoid tooth shape scales.
- Trygon have no air bladder and operculum. It need to swim constantly to avoid sinking in absence of air bladder.
- It has a poisonous sting at the base of tail. Sting is a modification of dorsal fin.
Torpedo
- It is commonly called as Electric ray.
- Torpedo has a thick flabby body with. Strong tail.Dorsal fin is large round and angular shape.
- It has an oval pectoral disc with straight edge.
- Torpedo have small spiracles with small knob.
- Five pairs gill slits are present on under side on disc.
- Torpedo has a short thick tail With skin fold.
- It has a triangular caudal fin with blunt corner.
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| Torpedo |
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- Torpedo have no air bladder and operculum. It need to swim constantly to avoid sinking in absence of air bladder.
- Fertilisation is internal. Male has clasper near pelvic fin and insert into cloacal of female.
- Reproduction is ovoviviparous because fertilized eggs are retained in body of female for development
- Body is covered by Placoid tooth shape scales.
- Electric organ of Torpedo are modified muscle tissue located at the base of pectoral fin.
- It use these organ to generate the electricity for defence , capturing prey and to find sensory location.
General Characters of Osteichthyes:
- It includes both marine and fresh water fishes with bony endoskeleton.
- Their body is streamlined. Mouth is mostly terminal.
- They have four pairs of gills which are covered by an operculum on each side.
- Skin is covered with cycloid/ctenoid scales.
- Air bladder is present which regulates buoyancy.
- Heart is two- chambered (one auricle and one ventricle).
🎥 Video Lesson: Class Osteichthyes (Bony Fishes)
Use the clickable timestamps below to jump directly to important NEET & NGSS topics in our video lecture:
- 00:00 — Introduction to Bony Fishes
- 01:01 — 2-Chambered Heart & Common Traits
- 02:43 — Cycloid & Ctenoid Scales (Must Know)
- 03:30 — Gills and Operculum Function
- 04:00 — Air Bladder (Swim Bladder) Mystery
- 05:15 — Reproduction & External Fertilization
- 05:55 — Marine Examples (Flying Fish, Sea Horse)
- 06:40 — Fresh Water Fishes (Rohu, Catla)
- 07:20 — Aquarium & Fighting Fishes
- They are cold-blooded animals. Sexes are separate. Fertilisation is usually external. They are mostly oviparous and development is direct.
Example of Osteichthyes:
Exocoetus
- It is commonly known as flying fish .
- It has streamlined body to counter the water current.
- It's formed tail has two lobe. Lower lobe is longer than upper lobe.
- It has wing like pectoral fin to glide up to more than five hundred feet
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| Exocoetus |
- It has enlarged Pelvic fin therefore called as four wing flying fish.
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- Mouth is wide with both teeth and jaws.
- Head is blunt with slopping forehead in front of eyes.
- Fertilisation is external. Male and female release sperm and egg🥚 in water same time.
- Reproduction is oviparous because fertilized eggs are developed into larva called fry .
- Body is covered by cycloid scale with blue and silver white in color on upper and lower side of body respectively.
- It have air bladder and operculum. It maintain buoyancy to swim constantly due to presence of air bladder.
Hippocampus
- It is commonly called as Sea Horse and bent horse in Greek.
- Sea horse has horse like head , tubular snout and toothless mouth.
- Tai is prehensile , used to grasp the corals and sea grasses.
- Eyes of Hippocampus are able to move independently to each other.
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| Hippocampus |
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- Sea horse can change the color to warn the predator through the camouflage.
- It has a cup like depression on the top of head called crown which is unique for sea horse.
- Male sea horse has pouch on the stomach to carry egg.
- It is found in marine warm and temperate countries around the corals and sea grasses.
- It uses its dorsal fin to swim rapidly and used its pectoral fin to steer. Caudal fin is absent.
- During mating , female sea horse deposit approx 1500 eggs into male pouch and male show parental care.
Labeo
- It is found in fresh water and called as Rohu.
- It has a streamlined elongated body with thick middle and tapering head and tail.
- It has cycloid scale with moderate size.
- It has paired pectoral fin, dorsal fin, ventral fin, anal fin, caudal fin.
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| Rohu |
- Mouth is terminal with thick lips Rohu has large eyes without eyelids with transparent cornea. It has a pair nostril infront of eyes.
- Large operculum or gill cover is present to cover the gills. It has a four pairs of gills slits.
- Skeleton and vertebral column is Bony.
Catla
- It is found in fresh water and called as Katla.
- It has a short body, laterally compressed with large head
- It has cycloid scale on body but head is devoid of scales.
- It has paired pectoral fin, dorsal fin, anal fin, forked caudal fin.
- Mouth is wide with prominent lower jaw.
- Catla has large eyes 👀 and visible under the head.
- It has completed lateral line with approx 40 scales.
- Large operculum or gill cover is present to cover the gills.
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| Catla |
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- It has a three row of pharyngeal teeth with define pattern.
- During Breeding season, male develop a tough pectoral fin and female develop a pink genital opening on abdomen.
Clarias
- It is commonly called as Magur and found in fresh water.
- It has a slender and elongated body. Head is flat with broad mouth.The skin is devoid of scales.
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| Clarias |
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- Dorsal and anal fin is long and without spines.
- Four pairs of Barbles are present around the mouth.
- Pectoral fin is strong and large with the skin.
- It's gill arches are modified into large accessory breathing orga
- Large operculum or gill cover is present to cover the gills.
- Villiform teeth are present in form of patches on jaws and palate.
Betta
- It is commonly called Fighting fish and domesticated in aquarium.
- It has a stream line body to swim smoothly.
- The skin is composed of overlapping scales.
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| Betta ( Fighting Fish) |
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- Beta fish is diurnal, carnivorous and territorial.
- Male individual has well developed feathers.
- These fishes are excellent swimmers and jumpers.
- Life span of Betta fish is 3 to 5 years. Male Betta fish build bubble nest.
🎯 NEET MULTIPLE CHOICE QUESTIONS
🔥 100% CHALLENGE
"Questions yahi se aayega... taiyari jeet ki!"
1. Consider the following statement and select the number of correct sentences for the Pisces.
1. They are Cold blooded animals and don't have ability to regulate the internal body temperature.
2. Heart has one auricle and one ventricle.
3. Pisces name has been given because they bear fins.
4. Fishes are Poiklothermal.
A. One B. Two
C. Three D. Four
Answer: D
2. Which of the following statement is not correct for the cartilaginous fish.
A. They are fresh water fish with streamlined body.
B. Vertebral column is cartilaginous
C. Notochord is present throughout the life
D. They are viviparous and have internal fertilisation.
Answer: A
3. Consider the following feature of cartilaginous fish and select the correct code:
1. Ventral mouth
2. Terminal mouth
3. Placoid scale
4. Cycloid scale
A. 1 and 4 B. 1 and 3
C. 2 and 4 D. 2 and 3
Answers: B
4. Which of the following statement is correct for the cartilaginous fish.
A. Gills are enclosed in gill cover called operculum.
B. They can maintain buoyancy due to swim bladder.
C. Teeth are modified of placoid scales which are backwardly directed.
D. Endoskeleton is composed of bone.
Answer: C
5. Which of the following is not a feature of the cartilaginous fish.
A. Powerful jaw
B. Tough skin
C. Predacaceous in nature
D. Minute ctenoid scale
Answer: D
6. Given below are two statements and select the correct option
Statement I : Cartilaginous fish does not has swim bladder.
Statement Il : They have to swim constantly to avoid sinking.
A. Statement l is true and statement ll is false.
B. Statement l is false and statement ll is true.
C. Both statement I and II is true.
D. Both statement I and II is false.
Answer: C
7. Consider the following statement of cartilaginous fish and select the correct code:
1. Gills slits are separate and without operculum.
2. In Male individual, Pelvic fin bear clasper.
A. Only 1
B. Only 2
C. Both 1 and 2
D. Neither 1 nor 2
Answer: C
8. Which of the following cartilaginous fish has Electric organ hence called as Electric ray.
A. Trygon B. Torpedo
C. Pristis D. Scoliodon
Answer: B
9. Match the list
A. Pristis 1.Sting ray
B. Trygon 2. Saw fish
C. Scoliodon 3.Dog fish
D.Carcharodon4.White shark
A B C D
A. 2 1 3 4
B. 1 2 4 3
C. 4 3 2 1
D. 4 2 3 1
Answer : A
10. In which of the following cartilaginous fish, Poison sting is present.
A. Pristis
B. Scoliodon
C. Carcharodon
D. Trygon
Answer: D
11. Which of the following statement is correct for the bony fish.
A. They are found in both fresh and marine water with streamlined body.
B. Vertebral column is cartilaginous
C. Notochord is present in adult stage
D. They are viviparous and have internal fertilisation.
Answer: A
12. How many pairs of gill are enclosed in operculum on each side bony fish.
A. Four B. Six
C. Two D. Five
Answer: A
13. Consider the following feature of Bony fish and select the correct code:
1. Ventral mouth
2. Terminal mouth
3. Ctenoid scale
4. Cycloid scale
A. 1, 3 and 4 B. 1,2 and 4
C. 2,3 and 4 D. 1,2 and 3
Answers: C
14. Which of the following fish has swim bladder to maintain buoyancy in swimming.
A. Exocoetus or flying fish
B. Pristis or saw fish
C. Scoliodon or Dog fish
D.Torpedo or Electric ray
Answer: A
15. Which of the following is not a feature of the Bony fish.
A. Internal fertilisation
B. Saxes are seprate
C. Oviparous
D. Indirect development
Answer: D
16. Match the list
A. Betta 1.Fighting fish
B. Labeo 2. Angel fish
C.Pterophyllum 3.Rohu
D.Exocoetus 4.Flying fish
A B C D
A. 2 1 3 4
B. 1 3 2 4
C. 4 3 2 1
D. 4 2 3 1
Answer : B
17. Which of the following pair is not correctly matched.
A. Exocoetus: Fighting fish
B. Clarias : Magur
C. Katla : Catla
D. Hippocampus: Sea horse
Answer : A
18. Which one of the following pair is aquarium fish.
A. Labeo and Katla
B. Torpedo and Trygon
C.Betta and Pterophyllum
D. Scoliodon and Carcharodon
Answer : C
19. Pick out the group of Fresh water fish.
A. Torpedo, Trygon, Betta
B. Labeo, catla, Clarias
C.Scoliodon, Carcharodon, Exocoetus
D. Pristis, Labeo, Clarias
Answer: B
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