Transcript CLASS PISCES: FISHES

PHYLUM CHORDATA
• Dorsal Notochord-long rod that supports the bodybecomes the vertebrae in most.
• Dorsal Nerve cord-becomes the central nervous system.
• Pharyngeal gill slits-openings in the throat for feeding &
breathing-becomes the Pharynx in humans.
• Tail-forms in embryos and extends past the anus.
Evolution of Fishes
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Primitive fishes lacked jaws and paired fins
Ancestral jawless fish ruled the seas during
Devonian Period: Age of Fishes
Evolution of Fishes
CLASS PISCES:
FISHES
CLASS PISCES
BECAUSE THERE
ARE 20,000 SPECIES
THERE ARE 3
SUBCLASSES
SUBCLASS
AGNATHA
(JAWLESS FISH)
SUBCLASS
CHONDRICHTHYES
(CARTILAGE)
SUBCLASS
OSTEICHTHYES
(BONY FISH)
Jawless Fishes = Agnathans
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No true teeth/jaw
Skeleton made of fibers/cartilage
Cartilage-strong supporting tissue (softer/more
flexible than bone)
Lack true vertebrae (keep notochord as adults)
ONLY VERTEBRATE PARASITES!
2 groups: Lampreys and Hagfishes
Lampreys
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Parasites
Sucker-like oral disks with teeth to grasp and
suck tissues/flesh
Hagfishes
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Detritivores
No eyes
Toothed tongue
Secrete slime
6 hearts
Tie into knot
Hagfish
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Cartilaginous Fishes =
Chondrichthyes
Sharks, Rays, Skates
Cartilage skeleton (no bone)
Sharks have thousands of teeth in rows
Skates and Rays glide with wing-like pectoral
fins (bottom-dwelling)
CARTILAGINOUS FISH
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850 Species of Sharks, Rays,
& Skates
Skeleton is made of cartilage.
S-shaped swimming/rigid
fins.
External Gill slits.
Store oils & constant motion
to stay afloat.
Scales are small bony plates
(at one time used as
sandpaper).
RAYS & SKATES
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Flattened body for a bottomdwelling niche
Spiracles & eyes on the
dorsal side.
Mouth, nostrils & gill slits on
ventral side.
Stingrays have a hollow barb.
Manta ray grows to 18’.
SHARKS
Close to 300 species.
 Largest fish in the worldWhale Shark.
 Can smell 1drop/blood
In 1 million parts/water.
 Lateral line detect
vibrations in the water
 Ampullae of Lorenzini
Sense changes in electrical
field.
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WHALE SHARK
Bony Fishes = Osteichthyes
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Bone skeleton (hard, calcified tissue)
Ray-Finned Fishes-fins formed from bony
spines covered by thin layers of skin (largest
group)
Lobe-Finned Fishes-fleshy fins with bones
(some jointed like arms/legs)…ex. Lungfish &
Coelacanth
Fish:
•Aquatic Vertebrates
•Paired Fins
Caudal fin Dorsal fin
•Scales
•Gills
Lateral line Scales Eye
Mouth
Anal fin
Pelvic fin
Pectoral fin
Operculum
(gill cover)
Feeding
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Herbivores, carnivores, parasites, filter feeders,
and detritivores
Digestive tract:
mouthesophagusstomachpyloric
cecaintestineanus (solid waste)
Enzymes added by liver and pancreas
Digestive System
Intestine
Esophagus
Stomach
Liver
Pyloric cecum
Mouth
Anus
Pancreas
Respiration
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Gills on sides of pharynx to exchange gases
Gill Filaments-feathery structures with
capillaries for gas exchange
Gill Rakers-prevents prey from escaping
through gills
Gill Arches-support and protect gills
Operculum-protective bony cover over gill
openings
Gills
Lungfish
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Adaptation to oxygenpoor water
Tube brings oxygen
from air into fish’s
mouth to “LUNG”
Circulation
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Closed system
2 chambered heart
Single loop: heartgillsbody (back to heart)
Fish Heart
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Sinus Venosus-sac that collects oxygen poor
blood from veins; sends blood toAtriumlarge muscular chamber; sends it toVentriclelarge muscular chamber that pumps blood; sends
it toBulbus Arteriosus-muscular tube that
connects toAorta-large blood vessel that
sends blood to gills
Fish Heart
Sinus Venosus
Ventricle
Atrium Bulbus arteriosus
Circulation in a Fish
Gills
Body
muscle
circulation
Digestive system
circulation
Heart
Brain and
head
circulation
Excretion
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Eliminate nitrogenous waste as ammonia
(urine)
Kidneys filter waste from blood
Kidney
Diffusion through gills
Response/Nervous System
•Well-developed nervous system with brain
•Eyes with color vision
•Taste/Smell
•Lateral Line System- detect currents/vibrations in water (sense
nearby fishes)
Brain
Olfactory Bulbs-smell (olfaction)
Cerebrum-smell (and voluntary
activities)
Optic Lobe-process info from
eyes
Cerebellum-coordinates body
movements
Medulla Oblongata-controls
internal organs
Olfactory
bulb
Cerebrum
Optic lobe
Cerebellum
Medulla oblongata
Movement
• Swim Bladder-internal gas filled organ to
adjust buoyancy in bony fish only
Movement continued…
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Contract paired sets of muscles
Fins propel
Dorsal/Ventral fins for stability (Dorsal/Anal)
Paired fins for fine movements/turning
(Pectoral/Pelvic)
Caudal fin for speed
Reproduction
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External/Internal fertilization
Oviparous-eggs (embryo) develop and hatch
outside mom’s body; obtain food from egg yolk
Ovoviviparous-eggs stay in mom’s body; obtain
food from egg yolk; young are “born alive”
Viviparous-embryos stay in mom’s body; obtain
food from mom; young are born alive
•Anadromous-live
in ocean but
migrate to fresh
water to breed; Ex.
Salmon
Migrations
• Catadromous- Breed
in the oceans but live
in freshwater
• Eels migrate to the
Sargasso Sea, they
spawn at depths of 300
meters and die when
done