Comparison of Chordates and Non-chordates

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Comparison of Chordates and Non-chordates
S.No.	Chordates	Non-chordates
1.	Notochord present.	Notochord absent.
2.	Central nervous system is dorsal, hollow and single.	Central nervous system is ventral, solid and double.
3.	Pharynx perforated by gill slits.	Gill slits are absent.
4.	Heart is ventral.	Heart is dorsal (if present).
5.	A post-anal part (tail) is present.	Post-anal tail is absent.
6.	Endostyle or thyroid gland present.	Endostyle or thyroid gland absent.
7.	Segmented muscles.	Unsegmented muscles.

Chordata Characteristics

Characteristic	Description
Phylum	Chordata
Basic Features	Notochord, dorsal hollow nerve cord, paired pharyngeal gill slits, bilateral symmetry, triploblastic, coelomate, organ-system level of organisation, post anal tail, closed circulatory system
Subphyla	Urochordata (Tunicata), Cephalochordata, Vertebrata
Urochordata	Notochord present only in larval tail
Cephalochordata	Notochord extends from head to tail region and persists throughout life
Vertebrata	Notochord present during embryonic period, replaced by cartilaginous or bony vertebral column in adults
Additional Features (Vertebrates)	Ventral muscular heart with two, three, or four chambers, kidneys for excretion and osmoregulation, paired appendages (fins or limbs)
Examples	Urochordata – Ascidia, Salpa, Doliolum; Cephalochordata – Branchiostoma (Amphioxus or Lancelet)

+-------------------+
|   Deuterostomes   |
+-------------------+
|                   |
|                   |
|    +--------------+------------------------+
|    |                                      |
|    |              Chordata               |
|    |                                      |
|    |  (Possess Notochord)                |
|    |                                      |
|    +--------------+-----------+----------+
|                   |           |          |
|                   |           |          |
|           Craniata (Possess Skull)    Cephalochordata (e.g., Lancelets)
|                   |                   |  (e.g., Amphioxus)
|                   |                   |
|    +--------------+-------------------+-----------------+
|    |              |                   |                 |
|    |        Myxini (Hagfishes)  Vertebrata            Urochordata (e.g., Tunicates)
|    |       (e.g., Hagfishes) (Possess True Vertebrae)  (e.g., Sea squirts)
|    |              |                   |                 |
|    |              +-------------------+-----------------+
|    |                                      |
|    +----------------------+---------------+
|                           |
|                  +-------------------------+-----------+
|                  |                         |           |
|                  |                         |           |
|    Agnatha (Jawless Vertebrates)            Gnathostomata (Jawed Vertebrates)
|    | (Includes Hagfishes, Lampreys)          |           |
|    +------------------------------------------+-----------+--------------+
|      |           |                         |           |              |
|      |           |                         |           |              |
|  Petromyzontida (e.g., Lampreys)  Chondrichthyes   Osteichthyes   Other Chordates
|                                  (e.g., Sharks, Rays) (e.g., Bony Fishes, Lungfishes, Coelacanths)
|                                                                        |
|                                                                        |
|                                                Tetrapoda (Four-Legged Vertebrates)
|                                                (Includes Amphibians, Reptiles, Birds, Mammals)
|                                                                        |
|                                                                        |
+------------------------------------------------------------------------+
|                                                                        |
|                           Other Deuterostomes                         |
|                     (e.g., Echinodermata, Hemichordata, Chaetognatha) |
|                                                                        |
+------------------------------------------------------------------------+

Cyclostomata Characteristics

Characteristic	Description
Class	Cyclostomata
Habitat	Ectoparasites on fishes, marine, migrate to fresh water for spawning
Body Structure	Elongated body, 6-15 pairs of gill slits for Respiration, sucking and circular mouth without jaws, devoid of scales and paired fins
Skeleton	Cartilaginous cranium and vertebral column
Circulation	Closed type
Life Cycle	Larvae metamorphose and return to the ocean after spawning
Examples	Petromyzon (Lamprey)belongs to Craniate as well asto Vertebrata , on the other hand Myxine (Hagfish) belongs to Craniate but do not belongs to Vertebrata

Chondrichthyes vs Osteichthyes

Characteristic	Chondrichthyes	Osteichthyes
Habitat	Marine	Marine and freshwater
Endoskeleton	Cartilaginous	Bony
Body Structure	Streamlined	Streamlined
Mouth Position	Ventral	Terminal
Notochord	Persistent throughout life	Replaced by vertebral column
Gill Slits	Separate, without operculum	Covered by operculum
Scales	Minute placoid scales	Cycloid/ctenoid scales
Teeth	Modified placoid scales, backwardly directed	–
Jaws	Powerful	–
Feeding Behavior	Predaceous	–
Air Bladder	Absent, Due to the absence of air bladder, they have to swim constantly to avoid sinking.	Present for buoyancy regulation
Heart	Two-chambered (one auricle and one ventricle)	Two-chambered (one auricle and one ventricle)
Special Organs	Some have electric organs (e.g., Torpedo), some possess poison sting (e.g., Trygon)	–
Temperature Regulation	Cold-blooded (poikilothermous), i.e., they lack the capacity to regulate their body temperature.	Cold-blooded
Sexes	Separate	Separate
Claspers	Claspers are specialized organs found in male cartilaginous fish, such as sharks, skates, and rays. They are located on the pelvic fins and are used during mating to grasp onto the female’s body. These structures are modified pelvic fins that have grooves or hooks, allowing the male to hold onto the female securely during copulation. Claspers are essential for successful reproduction in these species, as they ensure proper positioning and transfer of sperm from the male to the female during mating.	–
Reproductive Features	Internal fertilization, many viviparous	External fertilization, mostly oviparous
Examples	Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray)	Marine – Exocoetus (Flying fish), Hippocampus (Sea horse); Freshwater – Labeo (Rohu), Catla (Katla), Clarias (Magur); Aquarium – Betta (Fighting fish), Pterophyllum (Angel fish)

Amphibia vs Reptilia vs Aves vs Mammalia

Characteristic	Amphibia	Reptilia	Aves	Mammalia
Habitat	Aquatic and terrestrial	Terrestrial	Terrestrial, aerial, aquatic	Various habitats including polar ice caps, deserts, forests, etc.
Limbs	Most have two pairs	Two pairs (when present)	Two pairs, forelimbs modified into wings	Two pairs, adapted for various activities
Body Structure	Head and trunk, tail may be present	Covered by dry and cornified skin	Feathers present, forelimbs modified into wings	Presence of hair, external ears
Skin	Moist, without scales	Dry, covered by epidermal scales or scutes	Dry, without glands except oil gland	Unique in possessing hair
Respiration	Gills, lungs, and skin	Lungs	Lungs, supplemented by air sacs	Lungs
Heart	Three-chambered	Usually three-chambered, four-chambered in crocodiles	Four-chambered	Four-chambered
Temperature Regulation	Cold-blooded	Cold-blooded	Warm-blooded	Warm-blooded
Sexes	Separate	Separate	Separate	Separate
Fertilisation	External	Internal	Internal	Internal
Development	Indirect	Direct	Direct	Direct
Examples	Bufo (Toad), Rana (Frog), Hyla (Tree frog), Salamandra (Salamander), Ichthyophis (Limbless amphibian)	Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard), Crocodilus (Crocodile), Alligator (Alligator), Hemidactylus (Wall lizard), Poisonous snakes – Naja (Cobra), Bangarus (Krait), Vipera (Viper)	Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich), Pavo (Peacock), Aptenodytes (Penguin), Neophron (Vulture)	Oviparous-Ornithorhynchus (Platypus); Viviparous – Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel), Macaca (Monkey), Rattus (Rat), Canis (Dog), Felis (Cat), Elephas (Elephant), Equus (Horse), Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (Tiger), Panthera leo (Lion)

Comparison Table: Chondrichthyes vs Osteichthyes vs Amphibia vs Reptilia vs Aves vs Mammalia

Characteristic	Chondrichthyes	Osteichthyes	Amphibia	Reptilia	Aves	Mammalia
Body Structure	Streamlined body, cartilaginous endoskeleton	Streamlined body, bony endoskeleton	Head and trunk, tail may be present, moist skin	Covered by dry and cornified skin, epidermal scales or scutes	Feathers present, forelimbs modified into wings	Presence of hair, external ears
Gill Structure	Separate gill slits, no operculum	Four pairs of gills covered by operculum	Gills, lungs, and skin	Lungs	Lungs, supplemented by air sacs	–
Heart Chambers	Two-chambered heart (one auricle, one ventricle)	Two-chambered heart (one auricle, one ventricle)	Three-chambered heart (two auricles, one ventricle)	Usually three-chambered heart, four-chambered in some	Four-chambered heart	Four-chambered heart
Temperature Regulation	Cold-blooded	Cold-blooded	Cold-blooded	Cold-blooded	Warm-blooded	Warm-blooded
Limb Structure	No paired fins, circular mouth without jaws	Paired fins, terminal mouth	Most have two pairs of limbs	Two pairs of limbs (when present)	Two pairs of limbs, forelimbs modified into wings	Two pairs of limbs, adapted for various activities
Fertilisation	Internal	External	External	Internal	Internal	Internal
Development	Direct	Direct	Indirect	Direct	Direct	Direct
Cloaca	–	–	Alimentary canal, urinary and reproductive tracts open into a common chamber that opens to the exterior	–	–	–
Additional Characteristics	–	Air bladder for buoyancy regulation	Eyes have eyelids, tympanum represents the ear	No external ear openings, tympanum represents ear, scales shed	Presence of feathers, beak, hollow bones, crop and gizzard	Found in various habitats, presence of mammary glands, external ears, different types of teeth
Examples	Petromyzon (Lamprey), Myxine (Hagfish)	Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray)	Bufo (Toad), Rana (Frog), Hyla (Tree frog), Salamandra (Salamander), Ichthyophis (Limbless amphibian)	Chelone (Turtle), Testudo (Tortoise), Chameleon (Tree lizard), Calotes (Garden lizard), Crocodilus (Crocodile), Alligator (Alligator), Hemidactylus (Wall lizard), Naja (Cobra), Bangarus (Krait), Vipera (Viper)	Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio (Ostrich), Pavo (Peacock), Aptenodytes (Penguin), Neophron (Vulture)	Ornithorhynchus (Platypus), Macropus (Kangaroo), Pteropus (Flying fox), Camelus (Camel), Macaca (Monkey), Rattus (Rat), Canis (Dog), Felis (Cat), Elephas (Elephant), Equus (Horse), Delphinus (Common dolphin), Balaenoptera (Blue whale), Panthera tigris (Tiger), Panthera leo (Lion)