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Phylum Chordata Classification and Overview

  • General Overview:
    • Phylum Chordata (Xordalilar tipi) comprises approximately 4300043000 species adapted to aquatic, marine, and terrestrial environments.
    • The phylum is divided into three major subphyla:
    • Subphylum Acrania / Cephalochordata (Bosh skeletsizlar kenja tipi):
      • Class Lancelets (Lansetniklar sinfi).
    • Subphylum Urochordata / Tunicata (Lichinkasi xordalilar kenja tipi):
      • Class Thaliacea / Salps (Salplar sinfi)
      • Class Appendicularia (Appendikulyariyalar sinfi)
      • Class Ascidiacea / Ascidians (Assidiyalar sinfi)
    • Subphylum Craniata / Vertebrata (Bosh skeletlilar / Umurtqalilar kenja tipi):
      • Class Fishes (Baliqlar sinfi) — includes Cartilaginous Fishes (Tog'ayli baliqlar) and Bony Fishes (Suyakli baliqlar)
      • Class Amphibians (Amfibiyalar / Suvda va quruqlikda yashovchilar sinfi)
      • Class Reptiles (Reptiliyalar / Emaklab yuruvchilar sinfi)
      • Class Birds (Qushlar sinfi)
      • Class Mammals (Sutemizuvchilar sinfi)

Lancelet (Lansetnik) Anatomy, Morphology, and Biology

  • Overview and Physical Characteristics:

    • Belongs to the subphylum Acrania (Bosh skeletsizlar) within Phylum Chordata.
    • Body length ranges from 4−8 cm4 - 8\,cm
    • Coloration is light pinkish (och pushti rangli).
    • Distributed in marine environments such as the Black Sea (Qora dengiz).
    • Discovered and extensively studied by the Russian academician A.O. Kovalevskiy (A.O. Kavalevskiy).

  • Anatomical Structure and Morphological Features:

    • Mouth and Pre-oral Cavity: The mouth opening is situated inside a specialized pre-oral funnel (og'iz oldi voronkasi) surrounded by 10−2010 - 20 pairs of oral tentacles (paypaslagichlar).
    • Skull and Brain: Brain (bosh miya) and skull/cranium (bosh skeleti) are completely absent.
    • Musculature: Muscle segments are arranged along both sides of the body as longitudinal bands (22 yonida tasma shaklida joylashgan).
    • Skeleton: Formed exclusively by the notochord (xorda), which persists throughout the animal's entire lifecycle.
    • Fins: Fins consist of simple skin folds (teri burmalari).
    • Pharynx and Gill Apparatus:
    • The pharynx (halqum) features numerous slit-like gill openings (jabra teshiklari) along both lateral sides.
    • Skin folds covering the gill slits form the peribranchial/atrial cavity (jabraoldi bo'shlig'i).

  • Internal Anatomy and Organ Systems:

    • Respiration: Respiration occurs through the gill slits (jabra orqali nafas oladi).
    • Excretory System: Consists of specialized tubule structures resembling those of segmented ringed worms (halqali chuvalchangga o'xshash tuzilgan naychalar).
    • Sequential Organ Layout (Anatomical Order):
    1. Notochord (xorda)
    2. Neural tube / Nerve cord (nerv nayi) — positioned dorsally above the notochord
    3. Pharynx (halqum)
    4. Atrial cavity / Peribranchial space (jabraoldi bo'shlig'i)
    5. Atriopore / External opening (bo'shliq teshigi)
    6. Liver / Hepatic cecum (jigar)
    7. Intestine (ichak)
    8. Anus / Posterior opening (orqa chiqaruv teshigi)
    9. Gonads / Reproductive glands (jinsiy bezlar)
    • Circulatory System:
    • Closed circulatory system (yopiq qon aylanish sistemasi).
    • Heart is absent (00 heart chambers).
    • Blood flows in a clockwise directional loop: pumped from the ventral aorta toward the anterior portion of the body, and flows back through the dorsal aorta to supply the posterior body region (80%80\% of the length).
    • Characterized by distinct gill artery capillary networks.

  • Reproduction and Life Cycle:

    • Dioecious / Gonochoric organism (ayrim jinsli hayvon).
    • Lacks sexual dimorphism (jinsiy dimorfizm kuzatilmaydi).
    • Gonads are located as paired organs along the lateral walls of the atrial cavity (jabraoldi bo'shlig'i yon tomonida juft-juft bo'lib joylashgan).
    • Fertilization is external (tashqi urug'lanish); unfertilized eggs are shed into the water where fertilization and development proceed.

Anatomy and structure of Lancelet (Lansetnik)

General Fish (Baliqlar) Morphology and Anatomical Traits

  • General Body Characteristics:

    • Aquatic vertebrates with bodies flattened laterally (22 yondan siqilgan) and covered with protective scales (tangachalar).
    • Poikilothermic / Cold-blooded organisms (qoykiloterm / sovuq qonli).
    • Skeletal Characteristics:
    • Vertebral column consists of 39−4239 - 42 vertebrae (39−4239 - 42 umurtqa).
    • True rib cage / Thorax is absent due to the total absence of a sternum / breastbone (to'sh suyagi).
    • Limb girdles (kamar skeleti) are not directly connected to the spine, setting fish apart from tetrapod vertebrates.

  • Fin Classification and Structure:

    • Unpaired Fins (Toq suzgichlar):
    • Dorsal fin (orqa suzgich) — 1 ta1\,ta
    • Caudal / Tail fin (dum suzgich) — 1 ta1\,ta
    • Anal fin (anal suzgich) — 1 ta1\,ta
    • Paired Fins (Juft suzgichlar):
    • Pectoral fins (ko'krak suzgichlar) — 2 ta2\,ta
    • Pelvic / Ventral fins (qorin suzgichlar) — 2 ta2\,ta

External anatomical features and fin positions of fish

Anatomy and Biology of the Common Carp (Zo'g'ora Baliq)

  • Species Overview and Habitat:

    • Native to mountain rivers and freshwater bodies of Central Asia (O'rta Osiyaning tog' daryolari).
    • Reaches body lengths up to 1 m1\,m.
    • Body weight ranges between 8−16 kg8 - 16\,kg
    • Features a laterally compressed body covered in broad scales.

  • External Topography and Fin Placement:

    1. Head capsule (bosh qutusi)
    2. Operculum / Gill cover (jabra qopqog'i)
    3. Dorsal fin (orqa suzgich)
    4. Vertebral column / Spine (umurtqa pog'onasi)
    5. Anal fin (anal suzgich)
    6. Pectoral fin (ko'krak suzgich)
    7. Pelvic / Ventral fin (qorin suzgich)
    8. Caudal fin (dum suzgich)

  • Internal Organ Systems and Spatial Layout:

    1. Gills (jabra)
    2. Swim bladder (suzgich pufagi)
    3. Trunk musculature (muskullar)
    4. Vertebral column (umurtqa pog'onasi)
    5. Mouth opening (og'iz teshigi)
    6. Liver (jigar)
    7. Gallbladder (o't pufagi)
    8. Stomach (oshqozon)
    9. Intestine (ichak)
    10. Spleen (taloq)
    11. Anus / Anal opening (orqa chiqaruv teshigi)
    12. Urinary bladder (qovuq)
    13. Kidney (buyrak)
    14. Brain (bosh miya)
    15. Spinal cord (orqa miya)
    16. Ovary / Female gonad (tuxumdon)
    17. Genital pore (jinsiy teshik)
    18. Urinary pore (siydik chiqarish teshigi)
    19. Heart (yurak)

Anatomy and internal organ arrangement of the Carp (Zo'g'ora baliq)

Physiological Systems of Fish

  • Respiratory System:

    • Respiratory organ consists of gills (jabra) comprising four primary anatomical structures:
    1. Gill filaments (jabra qilchalari)
    2. Gill arches / Rakers (jabra ravoqlari / rasoqlari)
    3. Gill lamellae / Leaflets (jabra yaproqlari / saraq)
    4. Gill cover / Operculum (jabra qopqog'i)

  • Swim Bladder (Suzgich Pufagi) Structure and Functions:

    • Anatomically located dorsally above the digestive tract / intestine (ichagining ustida joylashgan).
    • Formed as a silvery gas-filled sac constricted in the middle to form 22 interconnected chambers.
    • Connected directly to the intestine via a narrow pneumatic duct (ingichka naycha orqali tutashgan).
    • Functions:
    • Hydrostatic control: Enables diving, surfacing, and maintaining neutral buoyancy at various water depths (suvning yuqoriga va pastga ko'tarilib tushish vazifasini bajaradi).