Transcript Fishes Final Powerpoint - GMCbiology

Phylum Chordata
Subphylum Vertebrata
Subphylum Vertebrata
3 Major characteristics of the phylum
Chordata:
1. A Dorsal Nerve Cord
2. Gills (pharyngeal slits)
3. A Notochord
Subphylum Vertebrata
5 Characteristics of Vertebrates:
1. Have a Backbone (vertebral column, spine)
2. The vertebrae enclosed and protect the
nerve cord
3. They have a complex brain – nervous
system
4. Bilaterally symmetrical body plan
5. Presence of an endoskeleton
Marine Fishes
• Fishes were the 1st vertebrates to evolve
from an invertebrate (probably the
chordate). They appeared more than 500
million years ago. Therefore, they are the
oldest and simplest of all the vertebrates
• They are the most abundant vertebrates in
species and individuals. There are ~ 22,000
species of fishes that make up ~ ½ of ALL
vertebrates
Marine Fishes
• Fishes feed on most types of marine plants and animals.
Many other animals feed on them as well. Therefore, they
play a key role in the Marine Ecosystem.
• Humans have many uses for fishes:
– They provide a vital source of protein
– They can be ground up and used as fertilizer or chicken feed
– They can be used to make leather, glue, vitamins, as well as many
other products
– They provide a sport for sports fisherman
– They can also be kept as pets
Marine Fishes
• All fishes are ectothermic, so their body
temperature is dependent on their
surroundings
• They have a 2-chambered heart and breathe
through gills
• Reproduce sexually through internal or
external fertilization depending on the
species
• MOST have Paired Fins
Marine Fishes
• MOST have scales
• All fishes have highly developed
sensory systems. Cartilaginous
and bony fishes have an
adaptation called the lateral line
system – it is a line of fluid-filled
canals that run along the sides of
a fish. The lateral line system
allows a fish to detect movement
and vibrations in the water so
that they can swim in the dark
or through complex coral reefs.
Marine Fishes
3 MAJOR CLASSES OF FISHES:
1. Class Agnatha – Jawless Fishes
2. Class Chrondichthyes – Cartilaginous Fishes
3. Class Osteichthyes – Bony Fishes
Subphylum Vertebrata
Fishes
Subphylum Vertebrata
*Cranium
*Vertebrae
Larvae of a jawless fish
Skeletal elements of a jawless fish
Subphylum Vertebrata
Jawless Fishes
Jawless Fishes
• They are the most primitive fishes alive
today
• They lack jaws so they feed by suction with
the aid of a round, muscular mouth and
rows of teeth
• Body is cylindrical and elongate (like eels)
• They lack the paired fins and scales that
most fishes have
Jawless Fishes – ancient diversity
Jawless Fishes – modern diversity
Hagfish
Lamprey
Jawless fish: Hagfish
Jawless Fishes: Hagfish
• Also known as slime eels
Click for Video
• Feed mostly on dead or dying fishes
• Occasionally bore into their prey and eat
them from the inside out
• They dig tunnels in the muddy bottom sea
floor as a place to live
• 20 known species
• Skin is used in manufacturing of leather
goods, and for bait
Jawless fish: Lamprey
Jawless Fishes: Lampreys
• Found in temperate (mild) regions
• Primarily freshwater fishes, some move to
the sea as adults
• They attach to other fish and suck their
blood or feed on bottom invertebrates
• There are ~ 30 species
Jawless Fishes – modern diversity
lampreys
Click for
Video
Jawed Vertebrates
Fossil placoderm
*Jaws
*Paired fins
Class Chondrichthyes
Cartilaginous fishes
Cartilaginous Fishes
• Include sharks, rays, skates, and ratfishes
• Have a skeleton made of cartilage – a material
lighter and more flexible than bone
• Have moveable jaws that contain well-developed
teeth
• Mouth is usually ventral
• Have paired lateral fins – efficent for swimming
• Have rough, sand-paper skin because of the
presence of tiny scales, placoid scales (which are
similar in composition to teeth
Class Chondrichthyes
Placoid scales
Paired fins
Class
Chondrichthyes
Shark Characteristics:
• Well adapted for fast swimming and hunting
• Described as “living fossils” because they are similar to
species that swam the seas 100 million years ago
– Have changed very little over time
• Have a caudal fin (tail fin) that is well developed and
powerful
• Have 2 dorsal fins
• They have paired pectoral fins that are large and pointed in
most species
Shark Characteristics:
• Most sharks swim continuously, forcing water through the
mouth, over the gills, and out through the gill slits
– Not all sharks need to swim continuously
• They have many rows of sharp, triangular teeth. If a tooth
is lost or broken it is replaced by another, which slowly
shifts forward from the row behind it (like a conveyer belt)
Shark Diversity
Shark Diversity – there are many variations to the shark body
Megachasma pelagios
Squaliolus laticaudus
Pygmy shark
megamouth shark
Shark Diversity
Whale shark
Goblin shark
Mitsukurina owstoni
Rhincodon typus
Shark Senses
• Olfactory organs can detect chemicals diluted 1/10 billionth their original
concentration
• Lateral line senses low frequency vibrations of prey over large distances
• Excellent vision, even in dim water, used at close range
• At close range, sharks are guided to prey by electric fields surrounding
all animals
Ampullae of Lorenzini
Ampullae of Lorenzini
Ampullae of Lorenzini
Shark Conservation
Manta birostris
Skates and
rays
Skates and Rays Characteristics:
• ~ 470 extant species
• Have dorsoventrally-flattened bodies and for the most part live
on the bottom of the sea (which means they are referred to as
demersal)
• Some rays look like sharks and some sharks look like rays in
appearance. However, only rays, skates and related fishes have
their gill slits on the ventral side of the body rather than on the
side as in sharks (ex Angel Shark and the Shark Ray)
Skates and Rays Characteristics:
• Their pectoral fins are also flat and greatly expanded
• Many stingrays have a whip-like tail usually equipped with
stinging spines for defense
• Poison glands produce venom that can cause serious
wounds to anyone who steps or falls on them, some may
even result in death
Electric Rays can deliver shocks up to
200 volts by use of specialized organs
located on each side of the head
Narcine brasiliensis
Skates and Rays Characteristics:
• Eagle, Manta, and devil rays are the few rays that don’t
spend most of their time on the ocean bottom
• Skates are similar to rays in appearance and feeding habits,
however they lack a whip-like tail and stinging spine
Netflix River Monsters Death Ray Video
Ratfishes or
chimaeras
Hydrolagus colliei
Ratfishes Characteristics:
•
•
•
•
•
~ 25 species
Are mainly deep-fishes
Their gill slits are covered by a flap of skin
Some have a long rat-like tail
They feed on crustaceans and mollusks
Class Osteichthyes
bony fishes – 24,000 living species
Class Osteichthyes – are the majority of the fishes
Bony skeleton
Mouth – is located at the anterior end
Teeth are usually fused to the jawbones
Complex and adaptable
Class Osteichthyes
Scales – are thin, flexible, and
overlapping; develop from bone
Fins usually consist of thin membranes that are suported by bony
spines, or fin rays.
- Some are flexible and used for propulsion and manueverability
Fins
and
tail
Operculum – is a flap of bony plates and
tissue that protects the gills
Swim Bladder – is a gas-filled sac just above the stomach
and intestine, allows for the heavy bony skeleton
Buoyancy
Fish diversity
BIOLOGY
OF FISHES
Ichthyology is the scientific study of fishes
Body Shape:
• Body shape is derived from a
fish’s lifestyle
– Sharks and marlin have a
streamlined body for fast
swimming
– Rays and skates are flat on the top
and bottom for life on the ocean
floor
– Eels have an elongate body because
they often live in narrow spaces
• Body shape can also help fishes
camouflage themselves. They can
be shaped to resemble sea
grasses, rocks, and corals
Body form
and niche
Flounder
Body form
and niche
seahorse
Body form
and niche
Porcupine fish
Body form
and niche
jawfish
Coloration
Coloration:
• Bony fishes can use color for camouflage
• The colored pigments are found in special cells located in the
skin called chromatophores
• The varying amounts of different in chromatophores results in
fishes of many colors
• Some can change color based on mood or reproductive
condition
• Warning coloration is when fishes that are dangerous,
poisonous, or taste bad reveal it to others by use of bright
colors
• Cryptic Coloration is when fishes blend with the environment
to deceive predators and prey
• Discriptive coloration is when fishes have the presence of
stripes, bars, or spots that help break up the outline of its body
Locomotion:
• Fish swim to obtain food, escape predators, and find mates.
• Most swim in a side to side rhythmic motion by use of bands of
muscles or myomeres
• Fishes that don’t swim in the standard side to side motion use
their fins to maneuver around in the water.
Feeding:
• Sharks are carnivores, but unlike most carnivores many feed
on prey larger than they are
• There are 3 species of sharks that are filter-feeders. They are
the whale shark, basking shark, and the megamouth shark.
They filter the water with their gill rakers, which are slender
projections on the inner surface of the gill. The spaces between
the gill rakers determines the size of food they capture. They
feed on small fishes, squids, or plankton.
• The protrusible jaws of bony fishes allow them to be flexible in
feeding habits than sharks.
• Most have well-developed teeth for catching, grasping, and
holding their prey, which is usually swallowed whole
Feeding
Jaw protrusion
Jaws
Filter feeding
anchovies &
sardines
Filter feeding
Gill rakers
Feeding:
• Deep-water fishes often have huge mouths and teeth
• Many bony fishes are non-specialists, so they will capture a
variety of prey
• Fishes that mainly feed on seaweeds and other plants are
known as grazers
• Some filter plankton with their gill rakers. These fishes are
very small in comparison to the filter feeding sharks. (like the
examples of sardines and anchovies in the previous slides)
These fishes live in massive schools. Plankton feeders are the
most abundant fishes in the ocean
Digestion:
• Flow of food through the digestive tract:
– Mouth to Pharynx to Esophagus to Stomach to Intestine to Anus
• Chemical digestion usually begins in the stomach
• Bony fishes typically have slender blind tubes at the anterior
portion of the intestine called the pyloric caecae, which secrete
digestive enzymes
• The pancreas also secretes digestive enzymes
• The liver is also important in digestion because it secretes bile
which is needed to breakdown fats. The liver is particularly
large and oil-rich in sharks; it can make up to 20% of their
body weight.
Digestion:
• The intestine of
cartilaginous fishes contains
a spiraling portion called
the spiral valve, which
increases the surface area of
the intestine
• The intestine absorbs
nutrients and passes them
into the circulatory system
to be spread out to the rest
of the body. Any
undigested material exits
through the anus
Circulatory System:
• All fishes have a 2-chambered heart located below the gills
• Closed Circulatory System
Circulatory System:
Deoxygenated blood comes into the heart from the body.
Gas exchange occurs in the gills and oxygenated blood is
then carried back to the body by blood vessels called
arteries. The arteries branch out into thin-walled capillaries
then come together and flow into the veins that then carry
deoxygenated blood back to the heart
Respiratory System:
• Fishes take in oxygen dissolved in water and release carbon
dioxide through paired gills. The gills are located in the
pharynx.
• Since gas exchange occurs at the gills and a fish gets its oxygen
from water the fish must make sure that water is flowing over
the gills all the time. In other words they irrigate the gills.
• Every gill has its own chamber, and each gill chamber opens to
the outside by a separate gill slit. The first pair of gill slits of
cartilaginous fishes is modified into spiracles, a pair of round
openings just behind the eyes. The spiracles allow the fish to
take in water even when the mouth is buried in the ocean
bottom.
Respiratory System:
• The gills on each side of bony fishes share a common gill
chamber, which opens to the outside through a single opening.
This way is more efficient at getting water to the gills.
• In gas exchange oxygen is diffused from the water into the
capillaries located in the gills. This can occur because the
oxygen level in the blood at the lungs is typically very low due
to the fact that the blood has already traveled to the rest of the
body.
Regulation of the internal environment:
• Marine fishes actually have blood that is less salty than
seawater therefore, they lose water by osmosis. They need to
replenish lost water or they will dehydrate, therefore they
osmoregulate. They do this by swallowing seawater. The salt
from the seawater is excreted by the kidneys.
Nervous System and Sensory Organs:
• Most fishes have a highly developed sense of smell. They use this
to detect food, mates, and predators
• Fishes have special sensory cells located in olfactory sacs on both
sides of the head. Each sac opens to the outside through nostrils.
• Fishes detect other chemical stimuli with taste buds located in the
mouth.
• Bony fishes rely on vision more so than cartilaginous fishes. They
have to move closer or farther away to focus.
• Fishes have a sense organ called the lateral line that allows them
to detect vibrations in the water
• The ampulla of lorenzi in cartilaginous fishes is a sense organ in
the head that can detect weak electrical fields, which helps locate
prey
• They have inner ears that perceive sound waves and can also be
used in equilibrium
Vision
Olfaction
Taste
Lateral Line
Lateral Line
Lateral Line
nerves
Lateral Line