This document summarizes key characteristics of chordates and classes of fish, including jawless and jawed fish. It describes: 1) The five characteristics of chordates and the classes of jawless fish (hagfish and lamprey), which have cartilaginous skeletons and sucker-like mouths. 2) The class Chondrichthyes (sharks and rays), which have cartilage skeletons, dermal placoid scales, and multiple rows of replacement teeth. Reproduction includes live birth and egg-laying. 3) The class Osteichthyes (bony fish), which have over 30,000 species with bony backbones, fins, and swim bladders.

1. THE FISHES
BY SAFIAAFRIDI

3. PHYLUM CHORDATA
FIVE CHARACTERISTICS OF CHORDATES
1. Hollow nerve cord- in vertebrates it differentiates into brain and
spinal cord
2. Notochord- flexible rod present at one stage in all chordates; in
vertebrates it differentiates into vertebral column that forms
around the nerve cord
3. Pharyngeal slits - pouches that connect pharynx with outside
(between mouth and esophagus). gills in sharks, fish; present in
terrestrial animal embryos but disappear later except eustachian
tube (connecting throat and middle ear)
4. Postanal tail- extends beyond anus; present at least in embryo;
regresses into tail bone in humans
5. Segmentation- reflected in arrangement of muscles & in
vertebral column

4. SUPRACLASS AGNATHA
(JAWLESS FISH)
Class Cephalspidomorphi (Lamprey)
 lives in ocean
Parasite and larvae are filter feeder
 attaches to other fish & sucks their blood due to the presence of
anticoagulant in their saliva
 adult sea lampreys lives in ocean , near the end of their lives they
migrate to the fresh water stream for spawning
Fertilization is external , egg hatch into ammocoete larvae.
Ammocoaete larvae grow from 7mm to 17mm over three years
and larvae metamorphosis in to adult by developing sucker like
mouth, teeth, tongue and feeding musculature
They begin journey to sea and return their headwater only for
spawning and then die.

5. SUPRACLASS AGNATHA
(JAWLESS FISH)
Class Myxini (Hagfish)
 Scavenger
 lives in the ocean
 known for its slimy secretions
Feed on soft bodied invertebrates, scavenger and dying fish
Both have cartilaginous skeletons
and sucker-like mouths

6. SUPRACLASS GNATHOSTOMATA
(JAWED FISHES)

7. CLASS CHONDRICHTHYES (SHARKS & RAYS)
Sub Class Elasmobranchii
 Include sharks, skates, rays, 700 species
 Have skeletons made of cartilage not bones (have bone jaw).
 Most saltwater/ very few freshwater
 Have no operculum (gill cover)
 Some must keep moving to breathe & others can pump water over
their gills
 Range in size from 1m to 10 m.
 Have different kinds of scales that feel and look more like
sandpaper. Skin is tough having dermal placoid scales which are
posteriorly pointed
 .

8. CLASS CHONDRICHTHYES (SHARKS & RAYS)
 Multiple rows of replacement teeth that steadily
move forward like a conveyor belt. Sharks can
lose up to 30,000 or teeth in their lifetime
 Most sharks are cold blooded
 Control buoyancy with large livers that excrete
oil
 Spiracle- a modified slit behind the eye, assists
the shark with taking in water during respiration
and plays a major role in bottom dwelling sharks

9. CLASS CHONDRICHTHYES (SHARKS & RAYS)
 Sub class Holocephali
 Includes 30 species, chimaera
 Large head with small mouth surrounded by
large lips.
 Narrow tapering tails which gives its common
name “ratfish”
 Teeth modified into large plates for crushing the
shells of molluscs.
 Lack scales.
 Have gill cover called an operculum.

10. CLASS CHONDRICHTHYES
(SHARKS & RAYS)
 REPRODUCTION
 Viparous- live birth
 Viviparous- eggs hatch internally
 Ovoviviparous- lay egg cases externally
(Called mermaid’s purse)
 Separate sexes
 Males have claspers

11. CLASS CHONDRICHTHYES
(SHARKS & RAYS)
 SENSORY
 Ampullae of lorenzini- electroreceptor organs
used to detect the electromagnetic fields all
living things produce. They number in the
hundreds to thousands.
 Lateral line system- detects motion or
vibrations in water

12. GENERAL ANATOMY OF A SHARK

13. GENERAL ANATOMY OF A RAY

15. CLASS OSTEICHTHYES
(BONY FISH)
 More than 2
 0,000 species
 Backbone made of bone
 Freshwater & saltwater
 Gills with operculum (few have lungs)
 Fins - dorsal, caudal, pectoral, pelvic, anal.
 Swim bladder- a gas filled sac that helps the
fish maintain buoyancy. sharks don’t have a
swim bladder
 Lateral line system

16. TYPES OF OSTEICHTHYES
 Sub class Sarcoptergyii
 First group Include lung fishes
 Muscular lobes associated with their fins
 Use lungs in gas exchange
 When fresh water lakes and river begin to stagnate and
dry they use lungs for respiration but cannot with stand
total drying
 They remain in aestivation for six months or more
 They can survive drying by burrowing into the mud and
leave a narrow air pathway by bubbling air to the surface
 when rain again fill the riverbed , they emerge from
burrow to feed and reproduce

17. TYPES OF OSTEICHTHYES
 Sub class Sarcopterygii
 Second group is Coelacanth
 It is large upto 80kg
 Have heavy scales
 Lives in fresh water lakes and rivers
 Latimeria is the closest living freshwater relative
of terrestrial vertebrates
 Sub class Sarcopterygii
 Third group include osteolepiform believed to
become extinct

18. TYPES OF OSTEICHTHYES
 Subclass Actinoptergyii
 Also called ray finned fishes because their
finns lack muscular lobes and are supported
by bony structures
 Most fish are this type
 Possess swim bladders
 It is divided into two ifraclasses

19. TYPES OF OSTEICHTHYES
 One group is Chondrosteans
 Contain many species that lived during 215-120
million years ago
 Only 25 species remain today
 Ancestors had bony skeleton but living
members have cartilaginous skeleton
 Have tail with large upper lobe
 Sturgeons and paddlefishes are the example of
chondrosteans

20. TYPES OF OSTEICHTHYES

21. TYPES OF OSTEICHTHYES
 Sturgeons
 Lives in sea and migrate to river to breed
 They are large upto 1000 kg
 Bony plates cover the anterior portion of the
body
 Heavy scales covers the tail
 Mouth is small and jaws are weak
 Feed on invertebrates and they stir up from sea
or riverbed using their snout
 They are valued for their cavier (eggs), they
have been severly overfished

22. TYPES OF OSTEICHTHYES
 Paddle fishes
 Large, freshwater
 Have paddle like rostrum that is inverted with
sensory organs believed to detect weak
electric feilds
 Swim through the water with their mouth
open, filtering crusteceans and small fishes
 Found mainly in lakes and large rivers

23. TYPES OF OSTEICHTHYES
 Second group is Neoptergyii
 Garpike has thick scales and long jaws that it
uses to catch fishes
 Amia commonly called Dogfish or Bowfin
 Most living fishes are members of this group
and are referred to as teleosts or modern bony
fishes
 They have symmetrical caudal fin and swim
bladder that have lost its connection to the
digestive tract

24. NEOPTERGYII

25. FISH ANATOMY

26. THANK YOU