GENERAL CHARACTERS OF FISHES (PIECES)

Published in Zoology
Friday, 30 June 2017 00:12
Fishes are first evolved in silurian period of palaeozoic era. They increased their number in Devonian period. Devonian Period is Called Age of Fishes.
 
Fishes are first jawed vertebrates. They live in water. They are cold blooded vertebrates.
 
CHARACTERS
 
  1. Fishes are aquatic; cold blooded vertebrates.
  2. Their body is divisible into head, trunk and tail. Neck is absent.
  3. It has a spindle shaped body. It is helpful in swimming.
  4. The body is covered by scales. They are placoid scales, cycloid scales, ctenoid scales, ganoid scales etc.
  5. Respiration is by gills. Gills are the extensions of the pharynx. In the elasmobranches fishes, the gills will open separate. In bony fishes the gill slits are covered by operculum.
  6. On the head a pair of nostrils are present internal nostril are absent. In Dipnoi Internal nostrils are present
  7. On the head a pair of eyes is present.
  8. On the lateral sides of the body LATERAL LINE SENSE organs are present. They detect the pressure changes of water.
  9. The body shows paired and unpaired fins. Pelvic and pectoral fins are paired. Dorsal and ventral fins are unpaired. They maintain balance in water. They are useful for locomotion.
  10. The digestive system is well developed. In the intestine of shark scroll valve Is present. The nervous system contains brain and spinal cord. Brain is small & it will not occupy the entire cranial cavity.
  11. 10 pairs of cranial nerves are present.
  12. Kidneys are mesonephrlc.
  13. Urinary bladder is absent
  14. The skeleton of some fishes is made by cartilage. They are called cartilage fishes. In some fishes the skeleton is made by bone. They are called bony fishes.
  15. In some fresh water fishes accessory respiratory organs are present. They will take up aerial respiration.
  16. Sexes are separate. In male sharks claspers are present.
  17. Many fishes are oviparous. Some fishes are viviparous.
  18. In the development of fishes amnion is not developed. Hence these animals are called anamniotes.

Useful Sites

  • NCBI

    National Center for Biotechnology Information
  • LTO

    Lab Tests Online® by AACC
  • ASCP

    American Society for Clinical Pathology
  • ASM

    American Society for Microbiology
  • The Medical Library®

    Project of BioScience.pk
Advertisement

Connect With Us

Contact Us

All comments and suggestions about this web site are very welcome and a valuable source of information for us. Thanks!

Tel: +(92) 302 970 8985-6

Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Website: https://www.bioscience.pk

Our Sponsors

The Physio ClubB2BPakistan.com

By using BioScience.pk you agree to our use of cookies to enhance your experience on this website.