Transcript The mouth of a Lamprey

I. Jawless Fish:
-there are 2 types
-both are parasites
Unit 8
The Fishes
I. Jawless Fish:
-there are 2 types
-both are parasites
A. The Lamprey
1. Have no fins, jaws, scales or
bones
2. Are anadromous: born in
fresh water, migrate to ocean, and
return to fresh water to spawn
3. Life cycle: Hatch and live as
juveniles (4-6 years) in fresh water
a. Undergo “metamorphosis” (about
2 months) and become mature
b. Swim to ocean and live as
parasites about 2-3 years
c. return to streams and spawn
(reproduce)
d. die within 4 days
The mouth of a Lamprey
What Damage do Sea lampreys
Inflict on the Fishery?
Lampreys have been enormously destructive
since they invaded the Great Lakes. Sea
lampreys feed on body fluids, often scarring and
killing host fish.
• During its life as a parasite, each sea
lamprey can kill 40 or more pounds of fish.
Sea lampreys are so destructive that
under some conditions, only one of seven
fish attacked by a sea lamprey will survive.
Sea lampreys prey on all species of large
Great Lakes fish such as lake trout,
salmon, rainbow trout and others. Sea
lampreys have had an serious negative
impact on the Great Lakes fishery.
Because sea lampreys did not evolve with
naturally occurring Great Lakes fish
species, their aggressive, predaceous
behavior gave them a strong advantage
over their native fish prey. Their
aggressive feeding behavior contributed
significantly to the collapse of fish species
that were the economic mainstay of a
vibrant Great Lakes fishery.
For example, before sea lampreys entered
the Great Lakes, Canada and the United
States harvested about 15 million lbs. of
lake trout in lakes Huron and Superior
annually. By the early 1960s, the catch
was only about 300,000 lbs. The fishery
was devastated.
B. Hagfish
1. Has long eel-like body (16-32 inches)
2. Produces slime around its
body to protect against predators
3. Attaches to fish and sucks out
blood and tissue
The mouth of a hagfish
II. Cartilaginous fish
A. Are about 600 species
including sharks, skates and rays
B. Have no bones, only cartilage
Sting Ray
C. Have placoid scales - tiny teeth
deeply embedded in skin
.
placoid scales
Electron micrograph image of shark skin
D. Have visible gill slits for breathing
E. Have more rigid fins than bony fish
1. Rays
a. have flat bodies with
large pectoral fins
b. Many are bottom dwellers (move
along the bottom where they get
food)
c. Mouth and gills on underside
- have spiracles behind eyes
which bring clean water to
gills
spiracles
d. Most have tails which sting as
defense
Skates
What’s the difference between a
Ray and a Skate?
• The major difference between skates and
rays is the way in which they reproduce:
• Rays are viviparous (live bearing) while
skates are oviparous (egg laying), releasing
their eggs in rectangular cases sometimes
called "mermaid's purses".
• Also, Skates normally have prominent dorsal
fins while those of rays are absent or
reduced in rays.
III. Bony Fishes
-make up 95% of fish on Earth
-have a skeleton made of bone (including
a backbone)
-have mucus covered scales
A. Breathing
1. Have gills
2. Gills are covered by
operculum - flap of tissue which
opens and closes with each
breath
B. Movement
Use fins:
A. pectoral - paired on the sides
of the body (similar to front or
upper limbs in animals)
B. pelvic or ventral - paired on
the lower side of the body near
the head (similar to back or lower
limbs in animals)
C. dorsal - fin on the upper side
of the body
D. anal - fin on the lower side of
body, near tail
E. caudal - tail fin
B. Speed
1. depends on body shape
2. uses caudal (back) fin
for greater speed
3. fastest fish:
swordfish, tuna,
dolphin, barracuda
Which fish are fast swimmers?
C. Buoyancy (ability to float)
1. Fish need to be able to float or
rise in water to rest
2. Have a swim bladder - a gas
filled organ to help with
buoyancy
Muscles contract (tighten) bladder shrinks and fish sinks
Muscles relax - bladder gets
bigger and fish floats
D. Anatomy of fish
1. Have a 1 way digestive tract (in
mouth and out anus)
2. Have closed circulatory system
(have blood vessels and
arteries)
3. Have 2 chambered heart
4. Have no external ears,
but good hearing
5.Have well developed
nervous system:
Have a lateral line small openings
(pores) on
sides of fish
that sense
vibration in
water.
E. Reproduction
1. Most have external
reproduction
2. Sperm and eggs are released
during spawning
3. During larval stage, fish live
as plankton
4. Stages that follow: post
larval, juvenile, and adult