PDF Chordates Lecture 1

Chordates Lecture 1  ‫ الحيىانية‬:‫المملكة‬ Kingdom: Animalia Subkingdom: Protozoa Class: Rhizopoda Locomotion by pseudopodia e.g. Amoeba. Class: Flagellata Locomotion by flagella e.g. Euglena. Class: Ciliata Locomotion by cilia e.g. Paramecium Cl...

Chordates Lecture 1  ‫ الحيىانية‬:‫المملكة‬ Kingdom: Animalia Subkingdom: Protozoa Class: Rhizopoda Locomotion by pseudopodia e.g. Amoeba. Class: Flagellata Locomotion by flagella e.g. Euglena. Class: Ciliata Locomotion by cilia e.g. Paramecium Class: Sporozoa Locomotion through the medium they live e.g. Plasmodium malaria  Subkingdom: Metazoa Subkingdom: Metazoa Branch : Parazoa They have no enteron e.g. spong. Branch: Enterozoa They have enteron. Division: Diploblastica The body is formed of two germ layers; ectoderm and endoderm. Phylum:Coelenterata e.g.Hydra.  Division : Triploblastica Division : Triploblastica The body is formed of three germ layers; ectoderm, mesoderm and endoderm. 1- Group: Acoelomata No true body cavity or coelom Phylum : Platyhelminthes e.g. Fasciola. 2- Group: Pseudocoelomata Perivisceral body cavity.No true body cavity or coelom. Phylum : Nemathelminthes e.g. Ascaris. 3- Group: Coelomata  Group:Coelomata Group:Coelomata Phylum: Annelida Phylum: Mollusca Phylum: Arthropoda Phylum: Echinodermata Phylum: Chordata Phyla: Annelida,Mollusca, Arthropoda, Echinodermata are termed invertebrates.They have no vertebral column or notochord. Phylum Chordata includes diverse animals which possess an axial skeletal rod extending throughout the length of the body which is known as notochord or chorda-dorsalis.From which the name of the phylum is derived.  Chordates share some characters with invertebrates 1- Triploblastic animals 2- Bilateral symmetry 3- Metameric segmentation Distinctive characters of chordates: The three main characters of chordates: 1- Notochord 2- dorsal nerve cord 3- Pharyngeal gill slits 4- Postanal tail 5- Closed circulatory system. Ventral heart. 6- coelom (schisocoel – enterocoel). 7- skin (epidermis and dermis). Closed circulatory system Early embryogenesis of Amphioxus Schizocoel Enterocoel ( splitting of mesoderm) ( from archenteron)  Phylum : Chordata ‫شعبة الحبليات‬ A- Subphylum : Urochordata B- Subphylum : Cephalochordata C- Subphylum : Vertebrata (Craniata) 1- Superclass: Agnatha 2- Superclass: Gnathostomata A) Group: Pisces (fishes) B) Group: Tetrapoda Class: Amphibia Class: Reptilia Class: Aves (birds) Class: Mammalia Subphylum: Urochordata: Animals which possess notochord and nerve cord in tail region of larval stage. After metamorphosis the tail diappears with notochord & nerve cord e.g. Ascidia. Subphylum: Cephalochordata: Animals which possess notochord and nerve cord along the entire length of the body and persists through the whole life e.g.Amphioxus. These two subphyla are known as Protochordata or (Acraniata) No vertebral column or cranium.  Phylum: Chordata ‫ الحبليات‬:‫شعبة‬ Group: Protochordata ‫ الحبليات األولية‬:‫مجمىعة‬ Subphylum: Cephalochordata ‫ الرأسحبليات‬:‫جحث شعبة‬ e.g. Branchiostoma lanceolatus (Amphioxus) )‫السهيم (أمفيىكسس‬ External features of Amphioxus Enlarged anterior part of Amphioxus ‫الجزء األمامى مكبر للسهيم‬ dorsal fin ‫ زعنفة ظهرية‬-1 myotome ‫ قطعة عضلية‬-2 notochord ‫ حبل ظهرى‬-3 rostrum ‫ البوز‬-4 vestibule‫ الدهليز‬-5 wheel organ ‫ العضو العجلى‬-6 oral cirri ‫ ذؤابات فمية‬-7 velum ‫ النقاب‬-8 gill bar ‫ عارضة خيشومية‬-9