Fish Tail Types and Their Significance for Movement
1. CAUDAL FIN
Shape is directly related to normal swimming speed
of the fish
Fast swimming fishes have stiff ,quarter moon
shape fin attached to a narrow peduncle
Most rover fishes or fishes with frequent swimmers
have forked fin
Deep bodied fishes have rounded , squarish or
slightly forked
Tail of most the bony fishes homoceral
Cartilaginous fishes have heteroceral
2. PROTOCERCAL
caudal fin extends around the vertebral column
present in embryonic fish and hagfish
3. THE HETEROCERCAL TAIL
is an ancient form,
possessed by only a few primitive fishes, such as sharks,
sturgeon, and paddlefish.
It was a necessary tail shape when fishes had no swim
bladders and were heavy in the front; if the fish tried to use
a symmetrical tail, it would have plunged toward the
bottom.
Instead, it developed a tail with a deliberately downward-
driving design and supplemented it with horizontal, plane-
like pectoral fins that transformed that downward force into
a horizontal, forward-driving force.
4. HETEROCERCAL
Heterocercal - primitive fish like sturgeons,
paddlefish, plus cartilaginous fishes
Superorder Chondrostei and Class
Chondrichthyes
6. DIPHYCERCAL
Vertebral column is straight reaching upto tip of tail and both the
lobes are equal. Derived from heterocercal
Diphycercal - lungfish and crossopterygians
Subclass Sarcopterygii (fleshy-finned)
7. HYPOCERCAL
Reversed heterocercal: vertebrae extend into the lower lobe of the
tail, making it longer
Vertebral column extends into lower lobe
Fossilized ostracoderms (anapsids)
8. HOMOCERCAL
Vertebrae do not extend into a tail lobe
Fin more or less symmetrical
Pointed, rounded, truncate (squared),
emarginate, forked, lunate
9. FISH TAIL INDICATES HOW THE
FISH MOVES AND LIVES AS WELL.
Types of fish tails:
1. truncated tail
good for maneuverability and short bursts of speed
not as much drag as the round shape
Examples: killifish
This kind of tail is commonly found on fish in coastal
embayments.
13. 3. ROUND TAIL
= Large amounts of
surface area for effective
maneuvering and
acceleration
= but creates drag causing
the fish to tire easily
Clown fish
Round tail
14. 4. EMARGINATE
= Effective acceleration and
maneuvering
= not as much drag as the round
and truncate tail
15. 5. LUNATE OR CRESCENT
shaped tails like those found on a
swordfish
not good for maneuvering
but allow for great speed over long
distances and
usually found on fish that live in the
open ocean.
18. 5. LUNATE OR
CRESCENT
shaped tails like those found on a
swordfish
not good for maneuvering
but allow for great speed over long
distances and
usually found on fish that live in the
open ocean.
21. SPINES
Most important attributes of the fins of fishes is the
presence or absence of spine .They are light
weighted and provide protection .Mostly in small to
medium sized fishes
Bottom fishes usually lack spine ;rely on cover or
cryptic coloration for protection
Spine are two type:1.True (bony)2.Thickned rays
True: Bony structure ,without segment and round in
cross section and often branched. E.g Most of the
teleost
Thickened rays: Stiffed hard rays, rays are
important supporting structure of the fins are
segment ,dumbbell shaped in cross section . Spine
in case of shark are modified placoid scales
22. COLORATION IN FISHES
• Majority of fishes are vividly and brightly colored.
• It’s one of the most common phenomena found
among the fishes.
• Enormous range of colors and patterns that
produced in fishes are generally related to their
environment.
• Normally, darker on the dorsal and lighter on sides or
ventral side. i.e gives them protection from above
and below.
23. GENERAL DESCRIPTION
• Free swimming; simple coloration, whitish belly, silvery lower
sides, back are blue or green.
• Bottom dwellers; strongly marked above while pale beneath.
• Coral reefs; most brilliantly & elegantly colored, includes
Cardinalfishes, butterflyfishes, triggerfishes, parrotfishes etc.
• Oceanic; silver in the upper; red in the middle range; and violet or
black in the greater depths.
25. SOURCES OF COLOR
• Due to schemachromes( optically produced or physical
configuration)&biochromes (true pigmentsbymolecule).
• Schemachromes:
• White: skeleton,gasbladder,scales&testes.
• Blue&violets:iris.
• Iridescent:scales,eyes&intestinalmembranes.
• Biochromes includes;
• Carotenoids; yellow,red.
• Chromolipoids; yellowtobrown.
• Indigoids;red blue&green.
26. CONTINUED..
• Melanin; black or brown
• Porphyrins & bile pigments;red,yellow,
green,blue,brown.
• Flavines;yellow often with greenish
fluorescence.
• Purines; white or silvery
• Pterins;white,yellow,red,orange.
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27. PRESENCE OF
BIOCHROMES
• Carotenoids and purines appear in fish skin Liver
,eggs and
eyes have carotenoids.
• Melanin occur in the endoderm & skin.
• Porphyrins found in muscle and blood.
• Bile pigments are found in skeleton and bile.
• Flavines are found in blood,muscle,spleen,gills,heart,
kidneys,eggs,liver & eyes.
• Purines are in the scales and eyes also.
• Pterins are in the eyes,blood, liver
,kidneys &stomach.
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28. SPECIAL CELLS FOR COLOR /
PIGMENTATIONS
Two kinds of cells; chromatophores & iridocytes
chromatophores impart true color
• Located in dermis of skin, either outside or beneath
the scales.
• Also found in peritoneum and deeply around the brain
and spinal cord.
Basic chromatophore
Erythrophores; red and orange.
Xanthophores; yellow.
Melanophores; black.
Leucophores; white.
29. IRIDOCYTES
• Called mirror cell, because they contain reflecting
materials that mirror colors outside the fishes.
• Having purines large crystals that are incapable of
movement.
30. SIGNIFICANCE OF COLORATION
• for communication with either the members of same
species (intraspecific) or with different species
(interspecific).
•Intraspecific signals;
• For sexual purposes
• Recognition of their parents e.g in
Hemichromis which are bright
during period of caring young ones.
•
Interspecific
signals;
For warnings or intimidating
potentialpredators.
31. RAPIDAND SEMI PERMANENT
ADJUSTMENT
• Rapid adjustment; is by pigment granules within the
chromatophores by expansion and contraction.
• Semi permanent; by an increase in numbers of
chromatophores as like artist increases the number of
stipples for shading.
32. Hormonal CONTROL
• Due to general agreement that
coordination of color change is by
interaction of nervous system and
hormonal control.
• In scyllium, darkening as a black
background response involve MDH(Melanin
dispersing hormone) & Paling on a white
background involves MAH(melanine
aggregating hormone).
• Also evidences found in some Teleosts (
Anguilla,
Ictalurus, and Fundulus)
33. FUNCTIONS OF COLORATION
(COTT,1940)
• Principal functions of
coloration are;
• Concealment; General color
resemblance
Variable color
resemblance
Obliterative
shading
•
•
•
•
Disruptive
coloration
Disguise
•
• advertisement
34. CONCEALMENT;
GENERAL COLOR RESEMBLANCE
• Important in resemblance b/w fish and its background. E.g
many coral reefs are very bright in colors according to
colors in that coral reefs.
• Some Fishes living over light shaded bottoms are light
colored but over dark bottoms the same species are dark.
35. VARIABLE COLOR RESEMBLANCE
• Ability of fish to change color gradually or rapidly to match
its background.
• Occurs in life history stages e.g in rainbow trout (stream
resident phase) is multicolored including dark spots(young)
and rosy sides in adults.While The same individuals in sea
are blue above and white below.
• Variations also occurs according to seasons, day or night.
• E.g trout occupying bright or partly shaded in summer while
in ice covered or extreme winter
they are evenly dark.
36. OBLITERATIVE SHADING
• Countershading, or Thayer's law, is a method of
camouflage in which an animal’s coloration is darker
on the upper side and lighter on the underside of the
body.
• Surface normally toward light source is counter-
shaded by darkening while surface toward shadow are
counterlighted.
37.
38. DISRUPTIVE COLORATION
• also known as disruptive camouflage or disruptive patterning.
• Surface of fish is covered by irregular patches of contrasted color &
tones that draw attention away from the original shape which they
have.
• Prevent or delay as long as possible recognition on sight.
41. DISGUISE
• Simply tends to reduce the resemblance of the fish to
itself.
• Deflective and directive marks are important here.
• Deflective marks are those which deflect the attack of
an enemy from a more or less vital part of the body to
some other part. E.g dark spot on the tail of the bowfin
• Directive marks divert the attention of prey from the
most dangerous part of the predators’ part. E.g in
stargazers feeding habit.
45. ADVERTISEMENT
• Coloration for advertise or reveal.
• E.g in Darters of American streams and also members of
the Perch family (Percidae) are the most brightly.
• Significance for sexual recognition.
• E.g of sticklebacks suggest value of color in sexual
recognition.
48. USE IN CLASSIFICATION
• Used often as character to separate taxonomic
units .
• Exact pattern of chromatophores are often in
genetic control, use in classification.
70. TAXONOMIC HIERARCHY OF FISHES:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Agnatha (Myxini, Cephalaspidomorpha ),
Chondrichthyes, Osteichthyes
71. THREE MAJOR CLASSES OF LIVING FISH
Class Agnatha: most primitive. Eg.
Lampreys and Hagfishes
Class Chondrichthyes: cartilagenous.
Eg. Shark, rays and skates
Ostiecthyes: bony fishes
72. CLASS AGNATHA
They lack jaw and a bony skeleton.
They lack true bones hence very
flexible.
Have smooth scales skin and soft to
the touch.
Have oral sucker (instead of jaws) in
the center of which is the mouth cavity.
74. AGNATHA- JAWLESS FISHES
Current scenario breaks Agnathans (now a
Superclass) into 3 separate classes.
Class Myxini – includes hagfishes.
entirely marine
cartilaginous skeleton without bony armor, no
hint of vertebral development
feed by boring into dead or dying fish with
raspy tongue
Hagfishes are the most primitive living
vertebrate
75. AGNATHA- JAWLESS FISHES
Class Pteraspidomorphi – Diplorhina (two
nostrils)
oldest documented vertebrate fossils
appear in late Cambrian-Devonian
paired nasal openings
Tadpole-shaped
most have bony head shields
All spp are extinct
76. AGNATHA- JAWLESS FISHES
Class Cephalaspidomorpha –
Monorhina (one nostril)
varied body shapes and varied lifestyles
single nasal opening
fossil forms heavily armored (Silurian-
late Devonian)
includes living lamprey (Order
Petromyzontiformes)
77. CLASS PLACODERMI
Many were active predators, ranging
in size from a few inches to 30 feet
Present evidence suggests that they
are unrelated to any living fishes,
although formerly thought to be
potential ancestors to
Chondrichthyes
79. CLASS CHONDRICHTHYES
Includes sharks, skates, rays, ratfish
Cartilaginous skeleton, secondary condition
with loss of bony armor and internal bone
First appear during Devonian (~380 mya),
peaked during Carboniferous and Permian
(350-230 mya)
Possess well developed jaws and paired fins;
jaws with true teeth
Mostly marine, but some FW representatives
81. CLASS OSTEICHTHYES (BONY FISH)
Represents the most numerous and diverse fish class
Bony skeleton retained from ancestral vertebrates
3 Subclasses – all with well developed jaws and paired
fins
Subclass Acanthodii – “spiny-sharks”
occurred from Silurian (~425 mya) into Permian (~230 mya)
covered by peculiar diamond-shaped scales
heterocercal tail = upper lobe longer than lower lobe (like
sharks)
well developed paired fins supported by a strong spine; include
the normal two pairs, plus up to 5 additional pairs
possess true teeth and bony plate (operculum) covering gill
region
