Transcript ch. 24 fish notes - Moore Public Schools

CHAPTER 24: FISH
SPRING 2016
DARLA WYATT
GENERAL INFORMATION
There are three extant classes of fish:
Chondrichthyes, Actinoptergyii and Sarcoptergyii
(over 26,000 species in these three classes)
General characteristics of all fish include:
A. all are aquatic, jawed vertebrates with
tetrapod limb arrangement of paired pelvic and
pectoral fins and endoskeleton made of either
bone or cartilage or a combination of both.
B. Epidermis covered with scales
C. the development of jaws with teeth
permitted predation of large and active food
sources.
GENERAL INFORMATION
D. Specialized sense organs for hearing, sight
and smell evolved with a tripartite brain.
Additional senses included the lateral line
system and some fish groups also developed
an electro-receptive system.
E. Complete digestive system
F. Bilateral symmetry
G. Closed circulatory system
H. All fish are dioecious (separate sexes)
GENERAL INFORMATION
I.
All fish have a two
chambered heart with one
Atrium and one Ventricle
J. Fish have various methods of
achieving neutral
buoyancy including two
types of swim bladders
and internal oil producing
organs. ( such as the livers
of sharks)
CLASS CHONDRICHTHYES
(850 species)
means “ cartilage fish”
A. Most are marine but 28 species live in
freshwater.
B. This class includes species which achieve the
second largest size in the animal kingdom,
second only to whales. The whale shark can
reach sizes in excess of 12 meters in length.
C. All chondrichthyians have a cartilagenous
endoskeleton
CLASS CHONDRICHTHYES
Vertebral column
D. All sharks have a
heterocercal tail in
which the top lobe
of the tail is longer
than the bottom
lobe and contains
the vertebra.
CLASS CHONDRICHTHYES
E. tooth-like dermal
denticles composed of a
dentine center covered
with enamel with distinct
points on the posterior
side, this is why a shark’s
skin feels so abrasive.
Their teeth are actually
modified scales called
Dermal denticles and why
their scales are called skin
teeth. The name of these
scales is Placoid
CLASS CHONDRICHTHYES
F. Sharks lack a swim
bladder so they achieve
neutral bouyancy by
maintaining a high
osmotic internal pressure
and having a large liver
filled with a light-weight
oil called squalene. They
can adjust the amount of
this oil in their liver to
adjust their body density
to ascend or descend
through the water
column.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
Represented by Sharks, Skates
and Rays
1. 825 species
2. 9 living orders
3. Form and Function
a.
b.
Heterocercal tail
Paired fins, pectoral and
pelvic, supported by an
appendicular skeleton, In
males, the pectoral fins are
modified into claspers which
are used in copulation. One
or two dorsal fins, most of
which have spines for defense.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
c. 5-7 gill slits, no
operculum
d. A pointed rostrum with
a ventral mouth
CLASS CHONDRICHTHYES
subclass Elasmobranchii
E.Have a well-developed jaw
with the upper jaw unfused
to the skull allowing for
access to large chunks of
food. Their teeth are
modified scales that grow
in rows with up to 7 rows of
new teeth waiting to spring
up into place to replace
teeth lost while feeding (
most sharks and rays loose
between 500 and 1200
teeth during their lifetime.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
F. Eyes are lidless and
large with well
developed vision
G. Digestive system
consists of a large
esophagus leading to a
J-shaped stomach . A
liver and pancreas
empties into a short
straight intestine.
Attached to the
intestine, is the rectal
gland which controls
the salt concentration
of the blood.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
4. PREDATORY LIFE-Sharks and Rays are wellequipped for predation. They track their prey
using certain senses in an orderly sequence.
a. initial detection is usual
from more than a kilometer
away using their large
olfactory organ
(can detect blood
1 part in 10billion)
CLASS CHONDRICHTHYES
subclass Elasmobranchii
b. prey may be located from fairly long distances by
the lateral line system.
c. at closer range, sharks switch to vision
LATERAL LINE
AMPULLAE OF LORENZINI
D. During the final stages of attack, the sharks are
guided to their prey by a unique system called the
Ampullae of Lorenzini ( tiny jelly filled tubes on the
ventral side of the rostrum) that detect electrical
signals, some sharks also use this system to detect prey
buried in sand.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
5. REPRODUCTION- all chondrichthyians are
dioecious with internal fertilization but there are
three different types of maternal support for the
developing embryo.
a. many elasmobranchs lay
large yolky eggs immediately
after fertilization, this type
of maternal support is called
oviparous, the eggs are housed
in a capsule called a
Mermaids Purse and may take
up to 2 years to develop
CLASS CHONDRICHTHYES
subclass Elasmobranchii
5b. Some elasmobranchs retain the young in
their uterus for a prolonged period while they
are being nourished by their yolks and are
then born alive, this type of maternal support
is called ovoviviparous.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
5C. Some species have true placental support
(just like humans)this is called viviparous with
live birth.
d. Once maternal support for the developing
embryo ends, so does all parental care.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
TYPES OF SHARKS
Coastal waters are inhabited by sharks of
Order Carcharhiniformes such as the
hammerhead, tiger, and bull, all are known to
attack humans.
Pelagic sharks such as the Great white
which can reach sizes to 6meters and the
Mako are some of the most dangerous to
humans
CLASS CHONDRICHTHYES
subclass Elasmobranchii
The largest fish of all is the whale shark, it is in
order Orectiloboformes and is a filter feeder
and not dangerous to humans at all.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
• The largest of the freshwater elasmobranchs is
the sawfish which can reach up t o 8 meters.
The front of their skull is elongated to form a
serrated toothed blade which can slash and
kill prey
CLASS CHONDRICHTHYES
subclass Elasmobranchii
• Almost one-half of all elasmobranchs are in
order Rajiformes, a group made up of
organisms with a dorso-ventrally flattened
body and greatly enlarged pectoral fins used
like wings for swimming. The gills are on the
underneath side of the body but the large
spiracle is on top of the head and used for
primary breathing to keep from clogging the
gills. Their teeth are adapted for crushing
molluscs and crustaceans, their main prey.
CLASS CHONDRICHTHYES
subclass Elasmobranchii
• The largest of this group is the Manta Ray(29’
across and 3000 lbs.)
Examples include: electric rays, stingrays, devil rays,
eagle rays and the terrible nightshocker.
CLASS CHONDRICHTHYES
subclass Holocephali
• Called Chimeras ,ratfish, ghostfish
1. 35 species
2. Diverged from the earliest shark lineage over
360 mya.
3. Similar to elasmobranchs, but have some unique
features
A.
B.
They lack scales
Jaw fused to skull with large plates modified for crushing
prey
C. 4 gills covered with an operculum
D. Lack a stomach
E. Deep sea benthic creatures
F. Long rat-like tail
G. Oviparous and lay mermaids purses
CHIMERAS OR RATFISH
Bony fish
Class Actinoptergyii
Class Sarcoptergyii
Class Actinoptergyii
• Ray-finned fish ( 24,000 species)
General characteristics
A. Endoskeleton of Bone
B. Modern fish have a Homocercal tail, some
primitive forms have a heterocercal tail ( caudal
fin) lungfish have a diphycercal tail
Class Actinoptergyii
C. Scales ctenoid
or cycloid in advanced forms,
scales are of ganoid
construction
in primitive forms.
Class Actinoptergyii
D. Respiration by gills
covered with an
operculum
E. Neutral buoyancy is
achieved with a
swimbladder gas may
be added or removed
from the swim bladder
by two methods.
Class Actinoptergyii
E. Neutral buoyancy is achieved with a swim bladder gas
may be added or removed from the swim bladder by two
methods.
1. The more primitive method is with a
physostomous bladder, the fish must swim to the surface
to gulp air and they expel it by burping air out of the
pneumatic duct that connects the swim bladder to the
esophagus.
2. the more modern method is with a physoclistous
bladder in which gas from the blood is absorbed or
secreted as needed from a vascular area that is
surrounded by a capillary bed called the rete mirable
which functions to trap gasses, primarily oxygen from the
blood
Class Actinoptergyii
F. Bony fish are
usually oviparous
with external
fertilization
G. Digestive
modifications
include spiral
valve in ancient
forms, modern
fish have gastric
caeca.
1. Liver
2. swim bladder
5. Stomach
6. intestine
3. roe
4. pyloric caeca
Class Actinoptergyii
H. Reproductive system of bony
fish is usually either
oviparous ( egglayers) or
ovoviviparous ( live-bearers)
There are no viviparous bony
fish. Males have a genital
pore for release of sperm
and urine. Ovoviviparous
male species have a
gonopodium which is a
modified anal fin for internal
fertilization. Bony fish have
no cloaca but separate
urogenital and anal openings.
Male sex organ in bony fishthe gonopodium
Class Actinoptergyii
subclass Chondrosteai
A. Means cartilage bone
1. this is an ancient group of fish that have
many shark-like characteristics such as a
heterocercal tail, a spiral valve in the
intestine . Endoskeleton primarly of
cartilage, scales ganoid in shape.
2. Examples include sturgeon, paddlefish and
the Bichir of africa which also possesses a
lung.
Class Actinoptergyii
subclass Chondrosteai
Class Actinoptergyii
subclass Neoptergii
B. Means “new fin”
1. one main group, the teolosts are made up
of all the modern ray-finned fish with a bony
endoskeleton, a homocercal tail, and scales in
shape either ctenoid or cycloid.
2. The second small group of ray-finned fish is
make up of the Gar and Bowfin, both of which
are freshwater and predatory with large teeth
and ganoid scales.
Class Actinoptergyii
subclass Chondrosteai
Class Sarcoptergii
Means “lobed fined”
6 species of lungfish and 2 species of Coelacanth
General Characteristics:
A. tail is diphycercal
B. skin is embedded with scales called Cosmine
made of a dentine center covered with thin enamel
much like human teeth.
C. Intestine with a spiral valve
D. Gill slits with an operculum
E. Swimbladder is vascular and can function as a lung.
In the coelacanth, it is filled with fat.
Class Sarcoptergii
Of the six surviving species of Lungfish, two are
in one genus and found in Australia. These
lungfish depend on gill respiration and cannot
survive for very long out of water.
•
The two species of African lungfish and the
two species of South American lungfish live in
freshwater streams and ponds that dry up in
the dry season and they can live out of water
for long periods of time, up to four years, they
bury in the mud and form a slime cocoon.
Class Sarcoptergii
The Coelacanth is called a “fossil fish” because they were
thought to be extinct for 70mya until one was brought
up in a deep sea drift net off the coast of So. Africa in
the 1940’s. A second type possibly a new species was
caught in 1998n off the coast of Indonesia.
These fish are large headed and heavy bodied with fleshy
lobed appendages that they use to walk on the bottom
of the ocean. They have an oil filled swim bladder and
have the largest eggs of any known fish, over 9 cm in
diameter. The eggs hatch internally.
Osmotic regulation
A. Freshwater fish are hyperosmotic regulators because
freshwater is extremely dilute and the salt conc. of
the body of freshwater fish is much higher so water
tends to flow into their bodies, defenses include an
opistonephric kidney which produces a very dilute
urine and salt absorbing cells in the gills move salt
from the water to the blood. Also, they never have to
take a drink.
B. Saltwater fish are hypoosmotic regulators with a
different set of problems. Because they live in a salty
medium with a higher conc. of salt than their blood,
they tend to lose water and gain salt so they risk
dying of dehydration. To compensate, the marine fish
drink seawater constantly and the gills secrete the salt
through salt secretory cells in the gills.
Responses to stimuli
a. Electrotaxis-attract or repelled by electrical
currents
b. Phototaxis-feeding in daylight hours
c. Chemotaxis-scent trails in water- feed or breed
d. rheotaxis-orient headfirst into water currents
TYPES OF SYMBIOSIS
Symbiosis is the close association between individuals of
two or more species
a. Commensalism-a relationship in which individuals of
one species benefit while the individuals of the other
species remain unaffected. Ex. Shark and remora
b. Mutualism-a relationship involving the mutual
exploitation and mutual benefit of two or more
species. Ex. Rasses and grouper
c. Parasitism-a type of symbiosis in which one species,
the parasite, lives at the expense of the other species,
the host. Ex. Candiru and human
Migration
There are two types of migration undertaken by
fish.
A. Anadromous migration occurs when adult
organisms live in freshwater but return to the
ocean to spawn Ex. Eels
B. Catadromous migration occurs when adult
organisms spend their life at sea but swim up
freshwater rivers to spawn. Ex. salmon