16Chordata

▢ Phylum: Chordata
▢ Introduction:
❖ Definition: Chordata refers to the presence of a stiff, supporting rod-like structure along the back called Notochord. (Gr., noton = the back; L., chorda = chord)
❖ Characteristics:
  1. Bilaterally symmetrical
  2. Metamerically segmented
  3. Deuterostomate
  4. Highly motile
  5. Crawlers
❖ Properties:
  1. Highly movable
❖ ChordateFeatures:
  1. Notochord
  2. Dorsal tubular nerve cord
  3. Pharyngeal gill slits/ Pouches
  4. Post anal tail
❖ OtherFeatures:
    ◈ Endostyle_or_Thyroid:
    ■ Description: An endostyle is a longitudinal ciliated groove on the ventral wall of the pharynx which produces mucus to gather food particles.
    ■ FoundIn:
    1. Urochordates
    2. Cephalochordates
    3. Larvae of lampreys
    ■ OtherNames: Hypopharyngeal groove
  1. Complete digestive tract
  2. Ventral, contractile blood vessel (heart)
  3. Presence of true coelom (Schizocoel in vertebrates and Enterocoel in protochordates)
▢ Classification:
❖ Group:
◉ Acraniata_Protochordata:
◈ Traits:
  1. Primitive chordates
  2. Vertebrae and paired appendages absent
  3. All protochordates are marine
◈ Sub-Phylum:
■ Urochordata:
● CommonNames:
  1. Sea squirt
  2. Tunicates
● Features:
  1. Notochord present only in the tail region of larva
  2. Exclusively marine, solitary or colonial, fixed or pelagic
  3. Body wall = tunic (connective tissue-like)
  4. Calcareous spicules present
  5. Retrogressive metamorphosis in adult
  6. Blood travels in both directions
● Examples:
  1. Ascidia (Sea squirt)
  2. Pyrosoma
  3. Herdmania (Sea potato)
  4. Ciona
  5. Molgula
  6. Salpa
  7. Doliolum
  8. Botryllus
● SpecialNotes:
  1. Ascidian comprises the largest class of tunicates
  2. Pyrosoma emits strongest light among marine organisms
■ Cephalochordata:
● CommonName: Lancelets
● Features:
  1. All four chordate features are present throughout life
  2. Notochord extends from tail to head
  3. Small, elongate, laterally flattened, nearly transparent, tadpole-like body
● Digestion: Filter feeders
● Circulation: No true heart; contractile vessels propel blood
● Excretion: Protonephridia with solenocytes
● Reproduction:
⟣ Sexes: Dioecious
⟣ Gonads: Numerous and metamerically repeated
⟣ Gonoducts: Absent
⟣ Asexual reproduction: Absent
⟣ Development: Indirect, includes free-swimming larva
● UniqueStructure: Wheel organ
● Examples:
  1. Branchiostoma (Amphioxus)
  2. Asymmetron
◉ Craniata_Euchordata:
◈ Sub-Phylum:
■ Vertebrata:
● Features:
  1. Advanced chordates
  2. Well-developed cranium and vertebral column
  3. Notochord embryonic; replaced by vertebral column in adults
  4. Cephalization with special sense organs (smell, sight, hearing)
● Groups:
⟣ Anamniota_vs_Amniota:
➢ Anamniota:
⬦ Definition: Vertebrates without amnion and other extra-embryonic membranes
⬦ Examples:
  1. Pisces
  2. Amphibia
➢ Amniota:
⬦ Definition: Vertebrates with amnion and other extra-embryonic membranes
⬦ Examples:
  1. Reptiles
  2. Aves
  3. Mammals
⟣ Poikilothermous_vs_Homoiothermous:
➢ Poikilothermous:
⬦ Definition: Cold-blooded, does not maintain constant body temperature
⬦ Examples:
  1. Pisces
  2. Amphibia
  3. Reptiles
➢ Homoiothermous:
⬦ Definition: Warm-blooded, maintains constant body temperature
⬦ Examples:
  1. Aves
  2. Mammals
⟣ Kidney_Types:
➢ Pronephric:
⬦ Stage: Earliest stage in human
⬦ PermanentIn:
  1. Lampreys
  2. Hagfish
  3. Tadpole of Frog
➢ Mesonephric:
⬦ DevelopsAfter: Pronephric
⬦ PresentIn:
  1. Fishes
  2. Amphibia
  3. Adult Frog
  4. Embryo of Mammals
➢ Metanephric:
⬦ FinalFunctional: In reptiles, birds, adult mammals
⬦ Feature: Contains Loop of Henle
● Division:
⟣ Agnatha:
➢ Features:
  1. Primitive vertebrates
  2. Endoskeleton fibrous and cartilaginous
  3. Notochord persists throughout life
  4. Without jaws and paired appendages
  5. Internal ear with one or two semicircular canals
➢ Classes:
⬦ Ostracodermi:
○ Notes:
  1. Extinct, first primitive vertebrates
  2. Body covered by bony armour
  3. Bottom dwellers, likely filter feeders
○ Examples:
  1. Cephalaspis
  2. Drepanaspis
⬦ Cyclostomata:
○ Features:
  1. Ventral, circular, suctorial mouth
  2. Eel-shaped, scaleless, jawless, no lateral fins
  3. Cartilaginous cranium and vertebral column
  4. Single, median nostril
  5. 6–15 pairs of pouch-like gill slits
  6. Closed circulatory system
  7. Ectoparasites or scavengers
  8. Marine, migrate to freshwater for spawning; die after spawning
○ Examples:
  1. Petromyzon (Lamprey)
  2. Myxine (Hagfish)
⟣ Gnathostomata:
➢ Features:
⬦ CranialNerves:
○ Pisces_Amphibia: 10 pairs
○ Rana_tigrina: 9 pairs
○ Man: 12 cranial, 31 spinal
○ Rabbit: 12 cranial, 37 spinal
➢ Super-Class:
⬦ Pisces:
○ Classes:
  1. Chondrichthyes
  2. Osteichthyes
⬦ Tetrapoda:
○ Classes:
○ Amphibia:
○ Reptilia:
○ Aves:
○ Mammalia:
○ Subclasses:
○ Protheria:
○ Order:
  1. Monotremata
○ Theria:
○ Infraclass:
○ Metatheria:
○ Order:
  1. Marsupials (Kangaroo)
○ Eutheria:
○ Orders:
  1. Insectivora
  2. Dermaptera
  3. Chiraptera
  4. Edentata
  5. Pholidota
  6. Rodentia
  7. Lagomorpha
  8. Carnivora
  9. Cetacea
  10. Sirenia
  11. Tubulidenta
  12. Proboscoidea
  13. Hyracoidea
  14. Perrisodactyla
  15. Artiodactyla
  16. Primates
○ Examples:
○ Lagomorpha:
  1. Rabbit
Q1.
Which of the following is present in embryonic stage also persists in some of the chordates
📅MOE 2002
Q2.
The elastic cord present in chordates above alimentary canal
📅MOE 1999
Q3.
The flexible rod on the dorsal surface in higher animal is called
📅MOE 2055
Q4.
Electric ray is
📅MOE 2062
Q5.
In which of the following does heart pump only deoxygenated blood.
📅IOM 2001
Q6.
Ophiology is the study of
📅IOM 1999
Q7.
Fangs of snakes are developed on
📅MOE 2063
Q8.
The muscular diaphragm is a distinctive character of:
📅MOE 2061
Q9.
Pinna is the characteristic of
📅MOE 2060
Q10.
Which of the following is not properly matched different from the other three animals
📅MOE 1999
Q11.
The distinguishing characteristic of the marsupials is the possession of
📅MOE 2000
Q12.
Which of the following is the correct way to write the scientific name of common dog?
📅MOE 2001
Q13.
Which of the following is true fish?
📅MOE 2000
Q14.
Parthenogenesis is
📅MOE 2056
Q15.
Birds and bats are good fliers. The bat differs from birds in having
📅MOE 2055
Q16.
Omosternum is absent in
📅MOE 2053
Q17.
Urinary bladder is absent in:
📅IOM 2007
Q18.
Most distinguished feature of eutherian mammals is presence of:
📅IOM 2006
Q19.
Animals without tail fall in:
📅IOM 2005
Q20.
Seminiferous tubules in vertebrates are lined with:
📅IOM 2005
Q21.
In viviparous animal, fertilization is:
📅IOM 2005
Q22.
The part of the ear that distinguish different pitches is the:
📅IOM 2004
Q23.
Most primitive placental mammal is:
📅IOM 2003
Q24.
In which of the following only oxygenated blood
📅IOM 2002
Q25.
Lateral line organ is found in:
📅IOM 2002
Q26.
Uric acid is the main nitrogenous waste product in:
📅IOM 2001
Q27.
The no. of cervical vertebrae in giraffe is:
📅IOM 2001
Q28.
When a bird is transferred from 30°C to 10°C, its body temperature:
📅IOM 1998
Q29.
Owls move freely during the night because they have:
📅IOM 1999
Q30.
Which of the following is a true fish?
📅BPKIHS 2007
Q31.
Lung fish (Lepidosiren) is found in:
📅IE 2008
Q32.
Poison glands of snakes are modified
📅IE 2003
Q33.
Amphibians are developed from
📅IE 2006
Q34.
Modern birds are closely related to
📅IE 2007
Q35.
In which of the following gills develop in association with pharyngeal pouches:
📅IE 2008
Q36.
A unique feature of mammalian body is presence of
📅IE 2009
Q37.
Which feature is different between birds and mammals?
📅IOM 2014
Q38.
Migration in birds is a result of
📅IOM 2014
Q39.
The fish green in colour
📅BPKIHS 2014
Q40.
Which one of the following is chordate character
📅BPKIHS 2014
Q41.
Pneumatic bone is found in
📅BPKIHS 2015
Q42.
A chordate may not have:
📅MOE 2014
Q43.
Non nucleated RBC is found in the class:
📅KU 2011