17Pisces

▢ Topic: General Characteristics of Fishes
▢ Details:
❖ 1. Ichthyology: The branch of zoology dealing with the study of fishes.
❖ 2. OrdovicianPeriod:
◉ Era: Palaeozoic
◉ Details: Fishes originated in the Ordovician period of the Palaeozoic era.
❖ 3. Ostracoderm:
◉ Description: Earliest known vertebrate fossils; jawless, bony-armored fishes.
❖ 4. BodyDivision:
◉ Parts:
  1. Head
  2. Trunk
  3. Tail
◉ Neck: Absent
❖ 5. Locomotion:
◉ FinsUsed:
  1. Paired pectoral fins
  2. Paired pelvic fins
  3. Median dorsal fin
  4. Caudal fin
❖ 6. TypesOfScales:
  1. Placoid
  2. Cycloid
  3. Ctenoid
❖ 7. Myotomes:
◉ Description: Muscles are arranged in segmental blocks called myotomes.
◉ MyotomeDefinition:
◈ General: Muscles served by a single spinal nerve root.
◈ Embryology: Part of somite that develops into muscles.
❖ 8. Heart:
◉ Chambers:
◈ Auricle: 1
◈ Ventricle: 1
◉ Type: Venous heart (pumps only deoxygenated blood)
◉ SinusVenosus: Present
◉ PortalSystems:
  1. Renal portal system
  2. Hepatic portal system
❖ 9. Kidneys:
◉ Type: Mesonephric
◉ Excretion:
  1. Ammonotelic
  2. Ureotelic
❖ 10. CranialNerves: 10 pairs
❖ 11. Ear:
◉ ExternalAndMiddleEar: Tympanum, tympanic cavity, and ear ossicles absent
◉ InternalEar: Contains 3 semicircular canals
❖ 12. LateralLineSystem: Lateral line receptors present for detecting vibrations and water currents.
❖ 13. Reproduction:
◉ Fertilization: Internal or external
◉ FemaleType:
  1. Oviparous
  2. Viviparous
◉ EggType: Macrolecithal (large eggs with much yolk)
◉ EmbryonicMembranes: Absent (Anamniotes)
◉ Development: Usually direct with little or no metamorphosis
❖ 14. Thermoregulation: Cold-blooded (Poikilothermic)
Category
Chondrichthyes / Cartilaginous fish
Osteichthyes / Bony fish
Type
Cartilaginous fish
Bony fish
Exoskeleton
Placoid scales
Cycloid or Ctenoid scales
Endoskeleton
Cartilages
Bone
Habitat
Marine fishes
  1. Both:
  2. i. Marine
  3. ii. Freshwater
Gill opening
Without operculum
With operculum
Mouth position
Ventral
Terminal
Characteristics
  1. a. Ampullae of Lorenzini: Chemoreceptor
  2. b. Maltese cross: Centrum with four cartilage
  3. c. Mermaid's purse: Shark egg capsule
  1. Possess Air bladder or Swim bladder:
  2. 1. Regulates Buoyancy
  3. 2. Acts as hydrostatic organ
  4. 3. Usually use lungs in gas exchange
Classes
  1. Elasmobranchii (Sharks, Skates, Rays)
  2. Holocephali (Chimaeras)
  1. Sarcopterygii (Lobe-finned fishes)
  2. Actinopterygii (Ray-finned fishes)
Examples (Sarcopterygii)
    1. 1. Neoceratodus (Australian lungfish)
    2. 2. Protopterus (African lungfish)
    3. 3. Lepidosiren (American lungfish)
    4. 4. Coelacanths:
    5. • Latimeria chalumnae – Caught off the coast of Africa
    6. • Latimeria menadoensis – Caught off the coast of Indonesia
    Examples (Actinopterygii)
      1. 1. Catfish
      2. 2. Flying fish – Exocoetus
      3. 3. Sea horse – Hippocampus
      Examples (Chondrichthyes)
      1. i. Great White Shark
      2. ii. Mako
      3. iii. Sting ray – Tail modified into defensive lash
      4. iv. Electric ray – Torpedo
      5. v. Rat fish – Chimaera
      6. vi. Scoliodon – Dog fish
        Q1.
        The scientific study of fishes is called
        Q2.
        Pisces are included under Gnathostomata because they usually possess
        Q3.
        Jawless vertebrates are placed under
        Q4.
        The single class of Agnatha is
        Q5.
        Cyclostomes are also called circular-mouthed fishes because they have
        Q6.
        Which of the following is an example of Cyclostomata?
        Q7.
        The larva of Petromyzon is called
        Q8.
        The body of Cyclostomata is usually
        Q9.
        The heart of fishes is
        Q10.
        The heart of fishes contains mainly
        Q11.
        The number of cranial nerves in fishes is generally
        Q12.
        The vertebrae of fishes are commonly
        Q13.
        The lateral line system of fishes mainly helps in detecting
        Q14.
        Superclass Pisces is divided into
        Q15.
        Chondrichthyes are fishes with
        Q16.
        Which scale is characteristic of Chondrichthyes?
        Q17.
        In cartilaginous fishes, the mouth is usually
        Q18.
        In Chondrichthyes, gill slits are generally
        Q19.
        Tail fin in Chondrichthyes is usually
        Q20.
        The main nitrogenous excretory product of cartilaginous fishes is
        Q21.
        Claspers in male cartilaginous fishes are used for
        Q22.
        Spiral valve is present in
        Q23.
        Ampulla of Lorenzini is found in sharks and acts mainly as
        Q24.
        Scoliodon is commonly known as
        Q25.
        Torpedo or Narcine is known for producing
        Q26.
        Osteichthyes are characterized by
        Q27.
        In bony fishes, the tail is usually
        Q28.
        Swim bladder in bony fishes mainly helps in
        Q29.
        Latimeria is important because it is
        Q30.
        Fish migrating from sea water to fresh water for breeding is called
        Q31.
        Fish migrating from fresh water to sea water for breeding is called
        Q32.
        Which of the following is a false fish?