Fish

1
Fish
2
What are Fish?

• Fish are aquatic vertebrates (animals with
  backbones) with fins for appendages.   They
  "breathe" by means of gills.
• Fish make up the largest of the vertebrate groups
  with well over 20,000 species.  Most taxonomists
  recognize 45 orders and 435 families of bony
  fishes.  They can be found in a great variety of
  habitats in lakes, streams, oceans and estuaries.

3
Classification

• Kingdom- Animalia
• Phylum- Chordata
• Sub Phylum- Vertebrata
• Classes- Agnatha, Chondrichthyes, Osteichthyes

4
Characteristics of Subphylum Vertebrata

• A notochord that has developed into a spinal cord
  protected byvertebrae and a head with a brain
  characterize organisms inthis subphylum.
• Vertebrates consist of the most complex, large,
  fast, and conspicuous organisms. They include us,
  the organism that has had the most effect on the
  global biosphere.
• Significance of Class Agnatha
• This is the class of the jawless fish.
• Species include lampreys and hagfish.
• Organisms in this class are significant because
  they mayrepresent the ancestor of bony
  fish/sharks.
• Scientists theorize that during the Cambrian
  period the firstof three gill arches on a
  jawless fish evolved into the first jaws.
• Having jaws allowed vertebrates to become very
  successful predators.
• Having jaws put organisms in class Chondrichthyes
  (sharks and rays) and class Osteichthyes (bony
  fish) near the top of marine food webs.

5
16.1
6
16.2
7
Classification of Fish

• Fish are classified according to the material
  which makes up their skeletons.
• Sharks, skates and rays belong to a group called
  cartilaginous fish because their skeletons are
  composed entirely of cartilage.  
• Tropical fish are called bony fish (scientific
  name Osteichthyes) because they have skeletons
  made of bone. 

8
Agnatha

• Jawless fish Lampreys, Hagfish

9
Types of Agnathans

• Hagfish- Ocean scavengers, not much is known
  about them.
• Lamprey- fresh and salt water, they are parasitic
  and prey on other fish.
• Both have cartilagenous skeletons and
  sucker-like mouths.

10
16.2
11
Chondricthyes

• Cartilagenous Fish Shark, Ray

12
Chondrichthyes

• Sharks are adapted for a predatory lifestyle.
• Cartilage skeletons, stiff pectoral fins (speed).
• No operculum, must keep moving to breathe.
• Have live births.
• Special scales feel like sandpaper.
• Manta, and Sting Rays- live in shallow water,
  have mouths located on the underside, are fairly
  docile, wide flat bodies and wing-like fins that
  are flexible.

13
Types of Chondrichthyes

• Sharks and Rays- have no operculum and must keep
  moving to breathe.
• Have different kinds of scales that feel and look
  more like sandpaper.
• Have skeletons made of cartilage not bones.

14
Characteristics of Sharks and Rays

• Class Chondrichthyes includes sharks, rays and
  their close relatives.
• Sharks and rays dont look similar on the
  outside, butshare a basic anatomy that
  classifies them together.
• Sharks and rays are jawed fish, that lack a swim
  bladder, and have cartilaginous skeletons.
• Special Attributes of Sharks and Rays
• Sharks and rays are successful predators
• Subclass Elasmobranchii have cartilaginous
  skeletons.
• This characteristic saves energy. Saving energy
  is one of thethings that have made them
  successful predators.
• Sharks have a sense of smell that detect
  incrediblydiluted substances.
• Sharks have a conveyor belt of multiple rows of
  teeth.
• They swing into place as old teeth wear out and
  fall away.

15
Special Attributes of Sharks and Rays (continued)

• Sharks and rays have other interesting
  characteristics
• Both have lateral lines lines of sensory hair
  along the length of the body that detect water
  motion and vibrations.
• Unique to elasmobranchs is electroreception the
  ability to sense minute electricity created by
  muscles and nerves.
• Sharks and rays have organs called ampullae of
  Lorenzini which you can see as visible pits near
  their snouts used to detect the electrical
  current.

16
Special Attributes of Sharks and Rays (continued)

• Elasmobranchs differ in their reproductive
  strategy.
• Sharks and rays produce fewer, but more mature
  offspring.
• Most fertilize their eggs internally.
• The male deposits sperm in the female via a pair
  of copulatory organs called claspers found at the
  base of the pelvic fins.
• The female lays an egg case in which the
  juveniles develop for up to six months at which
  time one or more sharks or rays emerge.
• A few shark species are ovoviviparous the eggs
  hatch within the mothers body.
• They give birth to live young rather than egg
  cases.
• The largest fish in the ocean.
• Shark size ranges from hand-sized to thewhale
  shark the largest fish in the ocean.
• Whale sharks can reach 14 meters (46 feet).
• Basking sharks can reach 10 meters (33 feet).
• Megamouth sharks can reach 6 meters (20 feet).
• All three are filter feeders that consume
  plankton.

17
Special Attributes of Rays

• Superorder Batidoidimorpha of subclass
  Elasmobranchii consists of therays, which
  includes skates and guitarfish.
• Ray anatomy is well suited to life on sandy
  bottoms or midwater.
• Specially adapted to life in midwater are the
  eagle ray and manta ray.
• Pectoral fins have become wings that stretch
  forward over the gills and are fused to the
  sides of the head.
• Shoulder girdles are flattened and many bones
  are fused together for rigidity.
• No longer need a tail for swimming, the tail has
  become a defensive whip in some species.
• Rays literally fly through the water.
• The largest rays are mantas with wingspans
  exceeding 8 meters (26 feet).
• Like the largest shark, the mantas feed on
  plankton.

18
Figure 8.14a
19
Figure 8.12a
20
Figure 8.04
21
Figure 8.05b
22
Figure 8.06b
23
Figure 8.07
24
Figure 8.08a
25
16.2
26
Fish Characteristics

• Gills
• Backbone (vertebrae)
• Paired Fins
• Single Loop Circulation
• Two chambered heart

27
Types of Osteichthyes (Bony Fish)

• Ray Finned
• Most fish are this type
• Fins are supported by bony structures called
  Rays.
• Teleosts are the most advanced form of ray finned
  fish (symmetrical tails and mobile fins).
• Lobe Finned
• Fins are long, fleshy, muscular, supported by
  central core of bones.
• Thought to be ancestors of amphibians.
• Examples are Coelacanth, Lungfish

28
Characteristics of Bony Fish

• Class Osteichthyes are jawed fish with bone
  skeletons.
• Most have a swim bladder and scales.
• Most control buoyancy by adding or releasing gas
  to/from their swim bladder.
• They control the swim bladders with oxygen gas
  exchanged to and from blood circulation.
• Many have a special organ called the gas gland
  and the rete mirabile that take up gases from the
  bloodstream for the swim bladder.
• This allows many species to hover nearly
  motionless in midwater.
• Most bony fish reproduce externally.
• The female lays her eggs, the maleimmediately
  fertilizes them.
• Their strategy is to produce a vast numberof
  off-spring with only a few expected to survive
  to maturity.

29
Characteristics of Bony Fish (continued)

• Bony fish have characteristics for life on the
  reef and for life in theopen ocean
• Bony fish have lateral lines that detect
  watermotion and vibrations.
• Most open ocean and schooling fish have a
  torpedo-likestreamlined shape that minimizes
  drag and turbulence.
• This fusiform shape is spindle-like, slightly
  broader at thehead and a V-shaped tail. This
  makes them fast swimmers.
• Most open-ocean and schooling fish have a lighter
  underside and dark topside for concealment.
• Bony fish living in reefs and on the bottom
  usesurvival strategies more diverse and
  includeconcealment and armor instead of
  swimming.
• For this reason, you see far more diversity in
  color,shape, and size among reef and bottom fish.

Bony Fish Half the Worlds Vertebrates
Chapter 5 Pages 5-74 5-75
30
Figure 8.08b
31
Fish Anatomy
32
Fins
33
Figure 8.12b
34
Figure 8.14b
35
Fish Anatomy
36
Fins
37
Fish Respiration

• Water flows over Gills as fish opens mouth and
  swims.
• Water flows opposite direction of blood flow.
• O2 diffuses from the water into the blood.
• Gills are made of thousands of gill filaments.
• Gills are covered by the Operculum.

38
Figure 8.15
39
Up Close and Personal
40
Gills

• Oxygen enters the bloodstream and carbon dioxide
  diffuses out at the gills, which are feathery
  structures found along the sides of the head.
• The gills of a healthy fish are bright red due to
  the high level of oxygen in the blood that is
  very close to the surface of the gills. (Without
  oxygen, the gills would be brown.)
• In bony fish, the gills are covered by a bony
  place called an operculum.

41
(No Transcript)
42
(No Transcript)
43
Skin

• The skin of most bony fish is covered with bony
  scales that look like shingles on a roof. 
• Bony fish scales are waterproof and help protect
  the fish.
• Glands in the skin in which the scales are
  embedded secrete a layer of mucus that covers the
  entire body

44

• Mucus helps protect fish from infection.
• Handling fish removes this mucus coating and can
  be harmful to the fish.

45
(No Transcript)
46
Shape

• The shape of a fish's body tells a lot about its
  lifestyle. 
• Fish with fusiform, or streamlined, bodies are
  usually fast swimming predators that may swim at
  high speeds much of the time or are capable of
  great bursts of speed.

47

• Many tropical fish are laterally compressed
  (flattened from side to side).
• Fish with this shape are not very streamlined but
  they do not rely on speed for catching food or
  escaping from predators. 
• Their body shape is perfectly adapted for hiding
  in the cracks and crevices of rocks and reef. 

48

• They can move into these areas to hide, to escape
  predators or to get at food that cannot be
  reached by other fish. 
• Fish with this body shape, like angelfish, are
  very maneuverable and capable of short bursts of
  speed.  
• They are often camouflaged with disruptive
  coloration.

49

• Other fish are flattened from top to bottom. 
• Fish with this body shape spend most of their
  time at the bottom. 
• They are usually camouflaged or can change color
  to match the bottom.

50

• Fusiform(Streamlined)
• Laterally Compressed(Flattened from side to side)

51

• Depressed(Flattened from top to bottom)
• Eel-Like(Body shaped like a snake)

52
Fins

• Fins are used for swimming and sometimes for
  protection. 
• Some fins are paired and others unpaired. 
• The paired fins are the pectoral and pelvic fins.
   
• The unpaired fins are the dorsal, caudal (tail)
  and anal fins.

53

• The way the fins are used varies among different
  groups of fish. 
• Most fish use their tails to move through the
  water and their other fins to steer with. 
• Fins are most bony fish are flexible and
  supported by visible spines and rays. 
• The shape, location and size of a fish's fins are
  closely linked with its way of life.

54
Pectoral Fins

• The paired pectoral fins are usually responsible
  for turning, although they can be used for other
  functions such as tasting, touching, support and
  as a source of power for swimming.

55
Pelvic Fins

• Paired pelvic fins add stability and are used for
  slowing some bony fishes.

56
Dorsal Fin

• This may be a single fin or be separated into
  several fins.  In most bony fishes, the dorsal
  fin is used for sudden direction changes and acts
  as a "keel" to keep the fish stable in the water.

57
Caudal (or tail) fin

• This is responsible for propulsion in most bony
  fishes

58
Anal Fin

• The anal fin adds stability.

59
Tails

• The shape of the tail can be an indicator of how
  fast a fish usually swims.
• Crescent-shaped Fish with crescent-shaped tails
  are fast swimmers and constantly on the move.
• Forked Fish with forked tails are also fast
  swimmers, though they may not swim fast all of
  the time.  The deeper the fork, the faster the
  fish can swim.
• Rounded Fish with a rounded or flattened tail
  are generally slow moving, but are capable of
  short, accurate bursts of speed.

60

• Fish with continuous caudal fins (dorsal, caudal,
  and anal fins attached) are able to swim in and
  around cracks and crevices.
• Fish with lunate caudal fins tend to be the
  fastest fishes and maintain a rapid speed for
  long durations.

61

• Many continuously swimming fish have forked
  caudal fins.
• Fish with truncate caudal fins are usually
  strong, but slow, swimmers.
• Fish with rounded caudal fins are usually strong,
  but slow, swimmers.

62
Eyes

• Fish are visual predators. 
• Many nocturnal fish have large eyes to help them
  feed at night. 
• Fish such as sharks have pupils that dilate and
  constrict, and some sharks also have an eyelid
  that closes from the bottom upward. 
• Bony fish eyes lack both of these
  characteristics.

63
Mouths

• The position of a fish's mouth gives a general
  indication of where it feeds in the water column.
• Fish with up-pointing mouths like hatchetfish
  primarily feed on the food flakes that float or
  hang near the water surface. 
• Some fish with mouths on the underside of their
  head, like the catfish, feed on the bottom. 

64

• Large For eating whole fish or chunks of fish
• Small For nibbling on plants and small animals
• Dorsal For eating near the surface

65

• Anterior For eating in the water column
• Ventral For eating on the bottom

66
Breathing Underwater

• Fish, like most organisms, need oxygen to
  survive. 
• The oxygen that fish "breathe" is dissolved in
  the water. 
• The oxygen enters the water surface by diffusion
  or in the water from plants as a byproduct of
  photosynthesis.

67

• Water enters the fish's mouth, moves across the
  gills and passes out the gill slits or
  operculum. 
• The gills are made up of a bony or cartilaginous
  arch supporting a large number of paired gill
  filaments. 
• Numerous small projections with very thin
  membranes on each filament are the sites of gas
  exchange (oxygen to carbon dioxide).

68

• Beneath the thin membrane is a network of blood
  vessels. 
• Oxygen diffuses from the water through the
  membrane into the blood and carbon dioxide
  diffuses outward.

69
Senses
70
Sight

• Most fish have well-developed eyes on the sides
  of their heads. 
• This placement allows them to see in all
  directions. 
• The structure of the eye is very similar to that
  of other vertebrates.

71

• In fish, focusing on near and distant objects is
  achieved by moving the lens backward and forward
  by muscular action. 
• Fish that are colorful can probably see in
  color. 
• Bony fish that are active at night have large
  eyes that help them see in the dark.

72
Smell

• Fish can smell odors in the water with receptors
  inside blind sacs, called nares, located on the
  head. 
• Nares are similar to our nostrils, but fish do
  not use them to breathe. 
• The sense of smell is well developed and is
  useful in detecting distant odors.

73
Taste

• For fish, taste is more of a close range sense. 
• Taste buds, which can be found on different parts
  of the fish, are used in the identification of
  food. 
• Taste buds are located in and around the mouth,
  and, on some fish, on the skin and even on the
  fins. 
• Barbels, whisker-like structures near the mouth
  of fish such as catfish, are covered with taste
  buds and are used in locating food.

74
Hearing

• Fish have ears but they do not open to the
  outside and cannot be seen.  
• Hearing in fish is well developed. 
• Water carries sound much better than air and the
  sound waves are picked up through the fish's body.

75
Lateral Line

• A line of holes runs along both sides of a fish
  from the head to the tail.  
• The holes have nerve connections that are
  sensitive to vibrations. 
• The lateral line is used form schooling, avoiding
  obstacles and detecting prey and predators.

76
(No Transcript)
77
Electroreception

• Some bony fish can detect weak electrical fields
  through pit organs on their heads and faces. 
• This ability is used for locating prey (all
  living things give off weak electrical fields),
  avoiding obstacles in murky water and in
  migrating.

78
(No Transcript)
79
Buoyancy

• Neutral buoyancy, the ability to remain
  motionless in the water without rising or
  sinking, is of great importance to a fish. 
• It allows a fish to spend energy feeding,
  escaping predators or mating that would otherwise
  be needed to maintain its position in the water. 

80

• Several strategies help achieve neutral buoyancy.
   
• Most bony fish have a structure called a swim
  bladder, which is a balloon-like organ in the
  body cavity. 
• Gases from the blood are added or removed to
  control buoyancy at different depths.

81
Fish Behavior

• Behavior is the action of a fish in response to
  its environment including other animals. 
• The most interesting and sometimes the most
  obvious behaviors involve interactions with other
  individuals.

82
Migration

• Many species of fish migrate during their life
  cycle. 
• It is well known that salmon make long migrations
  to spawn. 
• Other fish migrate in response to changing
  environmental conditions, such as temperature or
  abundance of food.

83
Schooling

• Many fish congregate in groups called schools. 
• A school is a group of similarly-sized fish of
  the same species aligned and swimming in the same
  direction.  
• Sight seems to be the primary means of
  maintaining the school. 
• The lateral line may also be used.

84
(No Transcript)
85
Aggression

• Aggressive behavior is an interaction between two
  fish of the same species (intraspecific) or
  different species (interspecific). 
• It is usually associated with reproduction or the
  defense of feeding territory. 
• It includes posturing, direct attacks and
  displays such as fin flaring and changes of color.

86
(No Transcript)
87
Resting

• Some fish spend a good portion of their day
  resting. 
• Resting reduces competition, provides protection
  from predators and may help in energy
  conservation.

88
Communication

• Senses play an important part in fish
  communication. 
• Visual communication is important to most fish. 
• Body movements, postures, colors and color
  patterns are the primary means of visual
  communication. 

89

• Sound is also used for communication.  
• Sounds are produced by grinding teeth, flexing or
  contracting muscles and vibrating the swim
  bladder.

90

• Fish also communicate by releasing chemicals
  called pheromones.  
• These are chemical signals produced by an animal
  that, when released, influence the behavior of
  others of the same species. 
• The sense of smell is important for this form of
  communication.

91
(No Transcript)
92
Cleaning

• Some tropical fish are cleaners. 
• They pick parasites from other fish.  Cleaning
  fish, such as wrasses, are brightly colored. 
• They establish cleaning stations that other fish
  approach in order to be cleaned. 
• Body posturing, a form of visual communication,
  is used to initiate cleaning.

93
(No Transcript)
94
Color
95
Red

• Red is a common color in fish. 
• You might think that red fish would be very easy
  for a predator to find. 
• However, most fish that have this coloration live
  in dark or deep water, or are nocturnal (active
  at night). 
• In deep water, red light is filtered out quickly
  so red is a good camouflage. 
• At night, red-colored objects appear gray.

96
(No Transcript)
97
Countershading

• Many fish are dark on top and light on the
  bottom. 
• When seen from above they "disappear" by blending
  in with the dark color of the depths of the
  bottom.  
• Seen from below, the light belly blends into the
  sky above.

98
Disruptive Coloration

• This is a form of camouflage. 
• The patterns and lines break up the outline of
  the fish and help it to blend into the
  background. 
• This confuses predators since the fish shape is
  not easily identifiable.

99
Eye Spots

• Eye spots are a form of mimicry. 
• They eye spot, usually found near the tail, may
  be used to draw attention away from the real eye
  which is a target that a predator might strike.

100
Warning Coloration

• Many fish use bright colors to "advertise" the
  presence of venomous spines or some other
  defensive mechanism

101
Camouflage

• Many fish have colors or patterns that match
  their backgrounds. 
• Some fish can even change color to match
  different backgrounds either to hide from prey
  (if an ambush is planned!) or to hide from a
  predator.

102
(No Transcript)
103
Food

• As a group, bony fishes have a diverse range of
  food preferences. 
• They may be herbivores (plant-eaters), carnivores
  (meat-eaters), omnivores (plant- and meat-eaters)
  or detritivores (animals that eat decomposing
  plants and animals). 
• Some of the animals common in the diets of bony
  fishes include worms, marine snails, mussels,
  clams, squids, crustaceans, insects, birds,
  amphibians, small mammals and other fishes.

104

• The amount of food a bony fish eats is directly
  related to its size, its metabolic rate and the
  temperature of its environment. 
• Warm water fishes, such as tropical fish,
  generally have higher metabolic rates and require
  more food than coldwater species of the same size.

105

• The esophagus in bony fishes is short, expandable
  and layered with muscles so that large objects
  can be swallowed. 
• Most species of bony fishes have a stomach with
  gastric glands that release substances that break
  down the food to prepare it for digestion. 
• The intestine is where the majority of food
  absorption takes place and the digestive system
  terminates at the anus.

106
Reproduction in Fish

• In most species of bony fishes, sperm and eggs
  develop in separate male and female individuals. 
  
• Fertilization is predominately external and, in
  some instances, internal. 
• Males and females may look similar, or they may
  look very different. 
• Male/female characteristics may include size,
  coloration, external reproductive organs, head
  characteristics and body shape. 

107

• While reproduction in bony fishes is generally
  cyclic, various factors may influence bony fish
  breeding such as changes in the duration of
  sunlight, temperature changes, moon stages and
  presence of spawning areas.

108

• Bony fishes show at least three types of
  embryonic development  egg layers (oviparous),
  egg retainers (ovoviviparous) and live bearing
  (viviparous). 
• Depending on the species, fish parents (male
  and/or female) may scatter, hide, guard or brood
  eggs. 

109

• There is great variation in the development stage
  at which offspring are released from the parent
  fish. 
• The number of offspring is inversely related to
  the chance a single egg has to reach maturity and
  reproduce in general, species whose eggs have
  little chance to reach maturity lay the most
  eggs. 
• For the most part, many species give no care to
  their eggs or young.

110
Figure 8.25
111
Fish Reproduction

• Most Fish reproduce sexually, and fertilize
  their eggs externally (Sharks-internally).
• Spawning is the process of fertilizing eggs.
• Baby fish are called FRY.

112
Fish Circulation

• Fish heart has 2 chambers
• Single loop circulation
• Blood flows into gills, picks up O2, goes to the
  body, returns to the heart.

113
Fish Adaptations

• Lateral Line System- used to detect vibrations,
  orient the fish in water, it is a line of cells
  running down the side of the fish.
• Operculum- gill cover, movement of operculum
  allows more water to be drawn in.
• Swim Bladder- a gas filled sac that helps the
  fish maintain buoyancy. Sharks dont have a swim
  bladder!
• Fins- Dorsal, Caudal, Pectoral, Pelvic, Anal.

114
Adaptations

• Air Bladder Operculum Lateral
• Gills
  Line

Fins
115
Figure 8.02
116
Figure 8.16a
117
Figure 8.16b
118
Figure 8.17a
119
Figure 8.17b
120
Figure 8.17c
121
Figure 8.17d
122
Figure 8.17e
123
Figure 8.18a
124
Figure 8.18b
125
Figure 8.19
126
Figure 8.22
127
Figure 8.24
128
Figure 8.28