A fish is an aquatic craniate animal that lacks limbs and has gills. They are classified in the kingdom Animalia and phylum Chordata. Early fish were small and jawless, while modern fish diversity increased with the evolution of jaws. Fish have scales, fins, and internal organs like gills for respiration and kidneys for excretion. They reproduce both sexually and asexually, and have a variety of habitats, diets, and behaviors.

2. What is a FISH?
A fish is any member of
a paraphyletic group of organisms that
consist of all gill -
bearing aquatic craniate animals that
lack limbs with digits.
Scientific classification
Kingdom: Animalia
Phylum: Chordata

3. History
Early fish from the fossil record are
represented by a group of small, jawless,
armored fish known as ostracoderms.
Jawless fish lineages are mostly extinct. An
extant clade, the lampreys may approximate
ancient pre-jawed fish. The first jaws are
found in Placodermi fossils. The diversity of
jawed vertebrates may indicate the
evolutionary advantage of a jawed mouth

4. CLASSIFICATION
 KINGDOM - ANIMALIA
 PHYLUM - CHORDATA
 SUB PHYLUM - VERTEBRATA
 CLASSES - AGNATHA
- CHONDRICHTHYES
- OSTEICHTHYES

5. DIFFERENT TERMS
 ANTERIOR (CRANIAL) : TOWARD THE HEAD
 POSTERIOR (CAUDAL) : TOWARD THE TAIL
 CRANIAL : HEAD REGION
 CAUDAL : PERTAINING TO THE TAIL REGION
 DORSAL : TOWARD THE BACK
 VENTRAL : TOWARD THE BELLY
 LATERAL : TO THE SIDES
 MEDIAL : TOWARD THE MEDIAN LINE
 DISTAL : AWAY FROM THE CENTER OR ORIGIN
 PROXIMAL : TOWARD THE CENTER OR ORIGIN
 BUCCAL : MOUTH REGION
 PECTORAL FINS : ON EACH SIDE BEHIND THE
OPERCULUM
 PELVIC FINS : ON VENTRAL SURFACE NEAR THE
HEAD
 ANAL FIN : BEHIND ANUS

6. EXTERNAL ANATOMY

7. INTERNAL ANATOMY

8. ANATOMY
Gills - Consist of threadlike structures called
filaments. Each filament contains a capillary network
that provides a large surface area for exchanging O &
CO2
Circulation - Fish have a closed-loop circulatory system.
The heart pumps the blood in a single loop
throughout the body.
In most fish, the heart consists of four parts,
including two chambers and an entrance and
exit. The first part is the sinus venosus, a thin-
walled sac that collects blood from the
fish's veins before allowing it to flow to the
second part, the atrium, which is a large
muscular chamber.

9. Digestion - Jaws allow fish to eat a wide variety of food, including plants
and other organisms. Fish ingest food through the mouth and break it
down in the esophagus. In the stomach, food is further digested and, in
many fish, processed in finger-shaped pouches called pyloric caeca,
which secrete digestive enzymes and absorb nutrients. Organs such as
the liver and pancreas add enzymes and various chemicals as the food
moves through the digestive tract. The intestine completes the process of
digestion and nutrient absorption.
Excretion - As with many aquatic animals, most fish release their
nitrogenous wastes as ammonia. Some of the wastes diffuse through the
gills. Blood wastes are filtered by the kidneys.
Saltwater fish tend to lose water because of osmosis. Their kidneys return
water to the body. Some fish have specially adapted kidneys that vary in
function, allowing them to move from freshwater to saltwater.
Scales - The scales of fish originate from the mesoderm (layer of
the dermis, which distinguishes them from reptile scales); they may be
similar in structure to teeth.

10. Central Nervous System
Fish typically have quite small brains relative to body size compared
with other vertebrates, typically one-fifteenth the brain mass of a
similarly sized bird or mammal. some fish have relatively large
brains, most notably mormyrids and sharks, which have brains
about as massive relative to body weight as birds.
FOREBRAIN – Olfactory Lobes – receive & process signals from
the nostrils.
MIDBRAIN – DIENCEPHALON connects the forebrain and the
midbrain.
HINDBRAIN or METECEPHALON – swimming and balance.
BRAIN STEM – Respiration and Osmoregulation.

11. Sense Organs
VISION- Fish eyes are similar to those
of terrestrial vertebrates like birds and mammals,
but have a more spherical lens.
RETINA – have rods and cones. Some fish can see
ultraviolet and others can see polarized light.
Adaptation to the environment.
Hearing - An important sensory system for most species of
fish.
Fish sense sound using their lateral lines and
their ears.

12. Fish reproductive organs
include testicles and ovaries.
SPERMATOGONIA OVARIES
Seminiferous
Tubules
Atherinomorph
Gymnovarian
Secondary
Gymnovarian

13. Larvae - The newly hatched young of oviparous fish.
- They are usually poorly formed, carry a
large yolk sac (for nourishment).
Ovoviviparous fish - Eggs develop inside the mother's
body after internal fertilization but receive little or no
nourishment directly from the mother, depending instead
on the yolk. (Guppies)
Viviparous - In such species the mother retains the eggs
and nourishes the embryos. (Lemon Shark).

14. • Most Fish reproduce sexually, and
fertilize their eggs externally
• Spawning is the process of fertilizing
eggs.
• Baby fish are called FRY

16. EDIBLE FISHES
FINFISH SHELLFISH
BASED ON
ANATOMICAL
DIFFERENCES

17. FIN FISH
FRESH
WATER
• SARDINE
• MULLET
• CATFISH
• PERCH
• PEARLESPOT
SALT
WATER
• SHARK
• SALMON
• MACKEREL
• SOLE
• TUNA

18. CLASSIFICATION
OF FISH
WHITE FISH BLUE FISH
BASED ON
MUSCLE COLOR

19. CLASSIFICATION OF
SEA FISH
PELAGIC
FISH
DEMERSAL
FISH
BASED ON
GROWING
CONDITION

20. MAJOR GROUPS OF
FISH
JAWLESS
FISHES
CARTILAGINOUS
FISHES
BONEY
FISHES
BASED ON STRUCTURE
OF MOUTH & TYPE OF
SKELTON

21. JAWLESS
FISH
(AGNATHA)
NO JAW,
NO SCALE
SKELETON
MADE OF
CARTILAGE
HAGFISH
LAMPREY

22. HAGFISH

23. LAMPREY

24. CARTILAGINOUS
FISH
(CHONDRICHTHYES)
MOVABLE JAW,
TEETH
ENDOSKELETONS
MADE OF
CARTILAGE
SHARK
RAY
SKATE

25. SHARK

26. RAY

27. BONEY FISH
(OSTEICHTHYES)
SKELETONS
MADE OF
BONE
SWIM
BLADDER
CATFISH
SALMON
GOLDFISH

28. CATFISH

29. SALMON

30. GOLDFISH

31. SCHOOLING – Refers to a group of fish
swimming together in the same direction
in a coordinated manner.

32. What do fish eat?
Fish usually eat each other, as well as
crustaceans such as shrimp, krill and
crabs.
They also eat kelp, algae and plankton,
as well as cephalopods such as squid
and octopus and also echinoderms such
as sea urchins

33. FISH HABITAT

35. Fastest Fish – Black Marlin 129km/h
Slowest Fish - Seahorse

36. ありがとう