comparative anatomy of chordates lect. 5 subphylum
TRANSCRIPT
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Subphylum Vertebrata
Superclass Agnatha
Comparative anatomy of Chordates
Lect. 5
Asst.lec. Sawsan S. Hameed
Biology Department
Tishk international University
2021-2022
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Objectives
- Understand the general characteristics of
Gnathostomata
- Differentiate between classes of Gnathostomata
- Describe and classify different species of
Gnathostomata
- Know the 3 orders of Chondichthyes, their
classification with examples of each
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Class Placodermi
fossil
Class
Chondrichthyes
Class
Osteichthyes
Agnatha
jawless vert.
Gnathostomata
jaw Vert.
Super class Super class
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Superclass Gnathostomata (jaw vert)
General Characteristic
➢ Vertebrates with jaws with teeth . ex; Human, fish, dogs,
cows, goats, cats
➢ paired nasal sacs.
➢ paired appendages (paired pectoral and pelvic fins)
supported by an internal skeleton
➢ Divided into 3 classes;
➢ Class Placodermi (extinct)
➢ Class Chondrichthyes (Cartilaginous fish)
➢ Class Osteichthyes (Bony fish)
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Class
Placodermi
Class
Chondrichthyes
C l a s s
O s t e i c h t h y e s
Selachi
or pleurutremata
Rajiformes or
Hypotremata
Chimaeriformes
Teleostie
Holostei
Chondrostei
Crossopterygi
Dipnoi
Superclass
Gnathostomata
(extinct)
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• Gr., Chondros= cartilage, ichthys =fish
• General characters
➢ Large, about 2m long, body fusiform.
➢ Most of the members are marine and are predators.
➢ Skin is covered by placoid scales.
➢ Endoskeleton is entirely cartilaginous, notochord
persistent but reduced,
➢ vertebrae complete and separate.
placoid scales
Class Chondrichthyes (cartilaginous fish)
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➢ Mouth is subterminal in position, two olfactory sacs that
do not connect to the mouth cavity.
➢ Jaws are with sharp teeth.
➢ True operculum is absent, instead, gill slits are present.
➢ paired pectoral and pelvic fins are present in addition to
the dorsal fins.
Class Chondrichthyes (cartilaginous fish)
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➢ Possess a variety of sensory systems, including senses
of smell, vision, hearing & sensory lateral line that
allows them to detect sound, vibration, and pressure
changes.
➢ Unisexual fishes, fertilization Internal
➢ males having claspers for reproduction.
➢ Clasper is a modified copulation organ from pelvic fin
➢ Gonads paired, reproductive ducts open into cloaca
Class Chondrichthyes (cartilaginous fish)
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Gr., Selakhe= a shark.
➢ Body typically spindle shaped.
➢ Gill slits 5 to 7, laterally located.
➢ Pectoral fin moderate, constricted at base.
➢ Caudal fin is heterocercal.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
subphylum Vertebrate
Class: Chondrichthyes
Order: Selachi
Order 1: Selachi (Squaliformes)
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➢ General features.
➢ Mouth is subterminal in position with hard
jaws are & numerous sharp teeth.
➢ Brain is developed & Powerful sensory
system helps in detection of food.
➢ Swim with high speed. The eggs are large & Gestation periods
for two years the longest period of any known living vertebrata
gill slits
mouth
Order 1: Selachi (Squaliformes)
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Whale shark Rhinocodon White shark Carcharodon
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Basking shark Cetorhinus maximus Zebra shark Stegostoma
Hammer headed shark Dogfish Chiloscyllium
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Dogfish Scolidon Dogfish Mustelus
Spiny dogfish Squalus Sawshark Peristiophorus
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(Gr., hypo=below , trema= opening).
➢ Body flattened, Spiracles large highly functional.
➢ Gill slits 5 pairs located ventrally so named Hypotremata.
➢ Pectoral fins enlarged like wings, fused with the head and body and used in swimming.
➢ The tail has changed to a whip-like organ of defense.
➢ They spend much time on the bottom
of the sea
➢ In giant mantas or devil fishes
(Manta, Mobula) many have
pectoral fin spread of 6 meters and
weight nearly half ton.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
subphylum Vertebrate
Class: Chondrichthyes
Subclass: Elasmobranchi
Order: Hypotremata
Order 2: Rajiformes or Hypotremata
Eagle ray Myliobti
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Pectoral fin
Sawfish Pristis
Guitar fishElectric ray Torpedo
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Those are remnants of a line diverged from the shark lineage
General features
➢ Body is somewhat compressed, and the skin is naked in adults.
➢ Endoskeleton is cartilaginous.
➢ Persistent notochord and poorly developed vertebrae.
➢ Bony plates are on the jaws instead of teeth used in crushing molluscan shells.
clasper
Scientific classification
Kingdom: Animalia
Phylum: Chordata
subphylum Vertebrate
Class: Chondrichthyes
Order: Chimaeriformes
Order: Chimaeriformes
EX; ratfish, rabbitfish, spookfish and ghostfish,
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➢ Upper jaw is completely fused to the cranium, most unusual feature in fishes.
➢ Untrue fleshy operculum hides the 4 gill slits.
➢ Pectoral fin broad and leaf-shaped.
➢ Males possess pelvic clasper on the head.
➢ Cloaca absent, anus and urinogenital aperture separate.
➢ Tail slender and whip-like.
➢ Feed mainly on benthic invertebrates
➢ Most species inhabit the deep
sea. Examples: Ratfish
Chimaera, and Harriotta
Order: Chimaeriform
Ratfish Chimaera
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Longnosed spookfish
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References
For further reading please see:
Charles K. Weichert (2017). Elements of chordate anatomy. 3rd edition.
The McGraw−Hill Companies, New york.
Comparative anatomy | Definition, Examples, & Facts |
Britannicahttps://www.britannica.com › science › comparative-anatomy
Kardong, Kenneth V. (2019). Vertebrates: comparative anatomy, function,
evolution (8th edition). New York.
De Iuliis, G., & Pulerà, D. (2019). The dissection of vertebrates. 3rd
edition. Academic press. Elsevier, London.
Kenneth, S. S. (2017). The unity of form and function. 8th edition. The
McGraw−Hill Companies,. New york.
Comparative Anatomy. wwww.health.zone/