Transcript The Fishes - lhsmedley

The Fishes
Vertebrate Success In Water
Cool Facts About Fish
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First animal to have a skull to
protect their brain.
41% of all fishes are freshwater
even though only less than
0.01% of the earth’s water is
freshwater.
It is estimated that there may
still be over 15,000 fish species
that have not yet been identified.
The largest fish is the great
whale shark which can reach
fifty feet in length.
The smallest fish is the
Philippine goby that is less than
1/3 of an inch when fully grown.
Fish have excellent senses of
sight, touch, taste and many
possess a good sense of smell
and 'hearing'.
Fish feel pain and suffer stress
just like mammals and birds.
Approximately
how long ago
did the first
true vertebrate
appear?
 About
510
million years
ago, during the
Cambrian
Period.
The 3 Classes
1. Agnatha- lack jaws and paired
appendages; ex. lampreys & hagfish
 2. Chondrichthyes – cartilaginous fish; ex.
sharks
 3. Osteichthyes – bony fish; beta fish,
salmon, trout, tuna, bass, goldfish,
guppies, etc.
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Class Agnatha
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Lack jaws.
Lack paired appendages.
Have a cartilaginous
skeleton.
Have a notochord that
persists into adulthood.
Ostracoderms are extinct
agnathans that had bony
armor for protection. They
were bottom dwelling,
filter feeders, about 1 foot
long.
Today’s agnathans are
hagfish and lampreys.
Class Agnatha: Hagfish
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Most primitive of all fish.
Hagfish are almost blind, but have
well developed senses of touch
and smell.
Hagfish live buried in the sand and
mud of marine environments.
They feed on soft-bodied
invertebrates and scavenge dead
and dying fish. When the hagfish
finds a suitable fish, they enter
through the mouth and eat the
contents of the body, leaving only
a sack of skin and bones.
Their metabolism is so slow that
they can go up to 7 months
without food.
Have 3 hearts.
Secrete a thick, slimy mucous,
and will even sneeze when the
mucous clogs their nostrils.
http://www.metacafe.com/w
atch/1597296/hagfish_and_
the_disgusting_slime/
Class Agnatha: Lamprey
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Common in both marine and
freshwater environments.
An adult lamprey has a circular
mouth, called an oral disc, that
exerts strong suction. Teeth
are located on the oral disc
and also on the tongue.
Adult lampreys prey on the
blood of other fish, while
lamprey larvae are filter
feeders.
Lamprey larvae are toothless
and blind. They burrow into
sediment at the bottom of a
stream where they feed on tiny
organisms that they filter out of
the water. After some three to
eight years, the larvae change
into adults. The adults die
soon after spawning (laying
their eggs).
http://www.geobeats.com/vide
Class Chondrichthyes
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Sharks, skates, & rays. (Rays
have live births, skates lay
eggs.)
Paired appendages for precise
steering an maneuverability.
Have jaws.
Cartilaginous body.
Carnivores and scavengers.
Most are marine.
Have scales that reduce
friction while swimming. In fact,
a shark’s teeth are just
modified scales that are
continually replaced
throughout its lifetime.
http://videos.howstuffworks.co
m/discovery/30421-perfectpredators-tiger-shark-teethvideo.htm
Shark Teeth
Myths About Sharks
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1. Sharks can’t hear because they
don’t have ears.
 Wrong! Sharks’ ears are on
the inside of their head and
they can hear very well!
2. Sharks have poor eyesight.
 Wrong! Sharks can see as
well, if not better, than we can.
3. Sharks have to swim
continuously in order to breathe.
 Wrong! Sharks have spiracles
that force water over the gills
even when the shark is at rest.
More about sharks!
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Currently, there are about 400
different species of known sharks!
Sharks are one of the most
formidable predators of the
oceans.
Like humans, sharks make use of
sight, sound, smell, touch and
taste--and they also have an
"electrosense" that gives them an
extra advantage underwater.
A shark's snout is dotted with jellyfilled, sensory pores called
ampullae of Lorenzini that pick up
faint electrical signals emitted by
even the quietest, best
camouflaged prey.
http://www.sharkwater.com/new_v
ideos/US%20Trailer%20Web%20
Finals/US%20Trailer%20w%20Blo
WHY DO WE NEED SHARKS?
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They are at the top of the food chain. Sharks feed on the
sick and weak, thereby keeping the schools of fish on
which they feed healthy. Lions and tigers serve the same
role in their respective ecosystems, removing the weaker
animals from the herds, and keeping the gene pool
strong.
Also, if the populations of these primary & secondary
consumers were to explode, they would consume all the
oceans’ algae. Humans and other animals need this
algae for the production of oxygen through
photosynthesis. Sharks keep these populations in
check, thus allowing us to breathe.
Skates & Rays
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Rays are usually larger than skates.
Rays give birth to live young while skates lay eggs.
Some rays (like the sting ray) contain venomous tails. Skates have
NO venom.
Rays usually have thinner tails, while skates’ tails are fleshier.
Class Osteichthyes: The Bony Fish
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Have a skeleton made of
bone.
Have an operculum – gill
cover.
Most have a swim
bladder to control their
depth in the water.
Two major types:
Coelacanths (lobe-finned
fish) and modern bony
fish (pretty much all the
fish we’re familiar with).
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The Coelacanth
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It has paired lobe fins that
extend away from its body like
legs and move in an
alternating pattern, like a
trotting horse.
Coelacanths are elusive, deepsea creatures, living in depths
up to 2,300 feet (700 meters)
below the surface. They can
be huge, reaching 6.5 feet (2
meters) or more and weighing
198 pounds (90 kilograms).
Scientists estimate they can
live up to 60 years or more.
studies in the Comoros
suggest only about 1,000
remain there. They are
considered an endangered
species.
Modern Bony Fish
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Streamlined to reduce friction
while swimming.
Secrete a mucous that further
reduces friction while
swimming.
Most are predators that spend
the majority of their day
searching for food. Some have
teeth, others do not have teeth.
If it is a filter feeder, it will have
gill rakers that trap plankton
while the fish is swimming.
Have a complete digestive
system that begins with a
jawed mouth, then lead to a
stomach, small intestines, and
ends at the anus.
Circulation & Gas Exchange
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Fish have a complete,
closed circulatory
system that works
with the gills to obtain
oxygen and deliver it
to the body.
Sensory Functions
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Fish have all the same senses we do, plus an
extra one- their lateral line.
The lateral lines are used to sense changing
water currents, indicating that a predator or prey
species is nearby.
Some even have a seventh senseelectroreception. This means that the fish can
sense the tiny amount of electricity that all living
things produce. This can help them locate prey
and avoid being prey for another fish.
Lateral Lines
External Anatomy of a Bony fish
Fin Identification and Purpose
Caudal fin – propulsion
 Dorsal fin – stability
 Pectoral fin – controls direction and
movement
 Anal fin – stability
 Pelvic fin – assists in moving up & down in
the water column
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Internal Anatomy of a Bony Fish:
Lung Fish
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Breathe air when lake
or river dries up
Have both gills and
one primitive lung
Fins are clumsy
Somewhat adapted
for life on land – but
not very well.
BCR
There are many important distinguishing characteristics
between the different classifications of fish. Explain the
characteristics used to group fish into different Classes.
In your response, be sure to:
 Identify and compare several criteria use by taxonomists
to classify fish.
 Describe the composition and function of scales in both
Chondrichthyes and Osteichthyes.
 Give an example of how each type of scale is
advantageous in its own environment (niche).
 Use appropriate scientific vocabulary.
Identify and compare several criteria
use by taxonomists to classify fish.
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Some of the characteristics that are used to
classify fish include:
 Number of gills
 Location of gills
 Type of snout/bill/mouth/chin
 Location of eyes
 Location of fins
 Types of fins
Compare: Venn Diagram
Describe the composition and function of
scales in both Chondrichthyes and
Osteichthyes.
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Osteichthyes – most have
ctenoid scales. These
overlapping scales grow larger
as the fish grows. The
overlapping gives the fish a
large range of movement as it
swims.
Chondrichthyes – have placoid
scales also known as dermal
denticles. These scales do not
overlap nor do they grow with
the fish. Instead, as the fish
grows, more placoid scales are
added.
Give an example of how each type of scale is
advantageous in its own environment (niche).
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Placoid scale advantages
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Counter shading of scales color
Well-developed sensory system embedded in scales.
Allow for deep dives and movement in shallow water
Reduces drag or friction in water
Ctenoid advantages
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Scales hold lateral line that allows for tubular canal bearing
sensory organs-they are sensitive to pressure and temp changes
in water currents.
Mucus on scales also makes capture more difficult
Light, thin and flexible, which increase mobility and speed.
Help to increase feeding efficiency or predatory avoidance