CEPHALOCHORDATA BY: NAJMA MOHAMED

Classification Information Common name: Lancelet Scientific Name: Cephalochordata Kingdom name: Animalia Phylum name: Chordata Class Name: Leptocardii

Common With Phylum All members of the Phylum Chordates have the following characteristics: Bilateral symmetry (equal halves) A segmented body, including segmented muscles, etc. Three germ layers and a well-developed coelom. A single, dorsal, hollow nerve cord, usually with an enlarged anterior end (brain). A tail projecting beyond (posterior to) the anus at some stage of development. Pharyngeal pouches present at some point in development. A ventral heart, with dorsal and ventral blood vessels and a closed blood system. A complete digestive system. A bony or cartilaginous endoskeleton is usually present.

Cont… Common Characteristics Symmetry: Bilateral Type of organism Free living Carnivore Aquatic

Life Cycle/Reproduction Average life span:500 million years ago How it reproduces: they reproduce by releasing their eggs and sperm into the water, where they are fertilized externally. The fertilized eggs develop into free-swimming larvae that drift in the water for up to 200 days, feeding on plankton and other suspended matter, before settling down as adults. a) Sexual b) Specific Characteristic: Overall blade-like shape with dorsal nerve chord supported by a muscular rod called a notochord1 • Pharyngeal slits – between the pharynx (throat) and the outside. They are supported by gill arches and used to strain food particles from the water. They are likely a primitive version of the gill found in more complex fish and amphibians

Habitat/ Niche Buried in the sand at the bottom of the ocean and sea, the tropical seas around Asia They mostly harvested humans and domesticated animals.

What are three special characteristics of the organism Interesting physical characteristics: 1) Lancelets look like slender fish without eyes. 2) Lancelets have blood vessels but no heart. Behavior: Depending on the coarseness of the habitat, cephalochordates assume different feeding positions. In coarse sediment they bury their body entirely within the substrate. The preferred position is with their anterior end exposed to the open water. In fine sediment they lie on the substrate. In southern china local fishermen using traditional techniques fish for and eat lancelets. The greatest importance of lancelets to people, however, is in the study of evolution.

Picture Video http://www.youtube.com/watch?v=SWkgQ02Hmqo&feature=player_detailpage

WORK CITED CHARACTERISTICS OF CHORDATES." Sam Houston State University - Texas - Carnegie Research Doctoral Univ. Web. 13 May 2011. <http://www.shsu.edu/~bio_mlt/Chap2.html>. Stanger-Hall, Kathrin F.. "Cephalochordata." Animal Sciences. 2002. Encyclopedia.com. 12 May. 2011 <http://www.encyclopedia.com>. Ramel, Gordon. "The Lancelets (Subphylum Cephalochordata)." The Earth Life Web. Web. 12 May 2011. <http://www.earthlife.net/inverts/cephalochordata.html>.