ABCS 341
(COMPARATIVE CHORDATE BIOLOGY)
PROTOCHORDATES AND FISHES
Prof. Daniel K. ATTUQUAYEFIO
Department of Animal Biology &
Conservation Science (DABCS)
University of Ghana, Legon
1
, INTRODUCTION
• Of the more than 65,000 living species of chordates, about half are bony
fishes (Class: Osteichthyes)
• The phylum Chordata includes the following subphyla:
– Tunicata (Salps and sea squirts)
– Cephalochordata (Lancelets)
– Vertebrata (Fishes, amphibians, reptiles, birds, and mammals)
• The first two subphyla are together known as the Protochordates
(primitive chordates), and all the other chordates belonging to the
Vertebrata are the Euchordates (modern chordates).
2
, INTRODUCTION (2)
• Six criteria used to determine the evolutionary branch of vertebrates
– Agnatha (Cyclostomes): Absence of mandibles (jaws) separates from other
vertebrates
– Pisces (Fishes): Absence of limbs (possess fins) separates them from
Tetrapods (terrestrial vertebrates)
– Chondrichthyes (Cartilaginous fish): Absence of bony (osseous) skeleton
separates them from Osteichthyes (bony fish)
– Amphibia: Absence of waterproof skin separates from other terrestrial
vertebrates
– Reptilia: Absence of warm blood (homeothermy) separates from Birds and
Mammals
– Aves (Birds): Absence of mammary glands and hair separates from Mammals
3
, PROTOCHORDATES
SYSTEMATICS
• Phylum: CHORDATA
Subphylum: UROCHORDATA (TUNICATA) – Tunicates (3,000 sp.) (Marine;
adults sessile, occasionally planktonic and enclosed in a tunic containing
cellulose)
Subphylum: CEPHALOCHORDATA (ACRANIATA) – Lancelets (30 sp.)
(Body laterally-compressed, transparent; fish-like, chordate characteristics
persist throughout life)
4
(COMPARATIVE CHORDATE BIOLOGY)
PROTOCHORDATES AND FISHES
Prof. Daniel K. ATTUQUAYEFIO
Department of Animal Biology &
Conservation Science (DABCS)
University of Ghana, Legon
1
, INTRODUCTION
• Of the more than 65,000 living species of chordates, about half are bony
fishes (Class: Osteichthyes)
• The phylum Chordata includes the following subphyla:
– Tunicata (Salps and sea squirts)
– Cephalochordata (Lancelets)
– Vertebrata (Fishes, amphibians, reptiles, birds, and mammals)
• The first two subphyla are together known as the Protochordates
(primitive chordates), and all the other chordates belonging to the
Vertebrata are the Euchordates (modern chordates).
2
, INTRODUCTION (2)
• Six criteria used to determine the evolutionary branch of vertebrates
– Agnatha (Cyclostomes): Absence of mandibles (jaws) separates from other
vertebrates
– Pisces (Fishes): Absence of limbs (possess fins) separates them from
Tetrapods (terrestrial vertebrates)
– Chondrichthyes (Cartilaginous fish): Absence of bony (osseous) skeleton
separates them from Osteichthyes (bony fish)
– Amphibia: Absence of waterproof skin separates from other terrestrial
vertebrates
– Reptilia: Absence of warm blood (homeothermy) separates from Birds and
Mammals
– Aves (Birds): Absence of mammary glands and hair separates from Mammals
3
, PROTOCHORDATES
SYSTEMATICS
• Phylum: CHORDATA
Subphylum: UROCHORDATA (TUNICATA) – Tunicates (3,000 sp.) (Marine;
adults sessile, occasionally planktonic and enclosed in a tunic containing
cellulose)
Subphylum: CEPHALOCHORDATA (ACRANIATA) – Lancelets (30 sp.)
(Body laterally-compressed, transparent; fish-like, chordate characteristics
persist throughout life)
4
