Structure | Function |
Olfactory sac | Enlarged, internal chamber of the nostril containing a sensory epithelium that allows the lamprey to "smell" dissolved chamicals in the surrounding water |
Pindeal organ | Photosensory organ located posterior to the nostril; controls many of the lamprey's activities that are dependent on photoperiod |
Eye | Image-forming photoreceptive organs that lack eyelids; each eye contains a lens and a pigmented retinal layer homologous to those present in other vertebrates |
Brain | Center of neural control; partitioned into a cerebrum, cerebellum, and medulla oblongata |
Notochord | Primary axial support element for the body |
Spinal cord | Posterior extension of the brain that lies dorsal to the notochord and contains spinal nerves |
Hypophyseal sac | Terminal region of the nostril that circulates water through the nostril and over the olfactory epithelium to facilitate olfaction |
Tongue (with teeth) | Muscular organ in the oral cavity that rasps through the body wall of the host to create seeping wounds for the lamprey to feed |
Oral gland | Secretes anticoagulating agent during feeding that prevents the host's blood from clotting and promotes blood flow |
Gill filaments | Highly vascular structures for gas exchange with the bloodstream |
Branchial pouch | Respiratory chamber that houses the gill filaments and receives water from the external gill slits |
Heart | Two-chambered organ (one atrium, one ventricle) that pumps deoxygenated blood to the gills for oxygenation and from the gills throughout the various organ systems of the body |
Sinus venosus | Thin-walled sac where deoxygenated blood from the body collects before being passed into the atrium of the heart |
Transverse septum | Partition that separates the coelom into the pericardial cavity and the pleuroperitoneal cavity |
Dorsal aorta | Channels oxygenated blood from the gills to the posterior regions of the body |
Ventral aorta | Channels blood from the heart to the gills for oxygenation |
Esophagus | Transports food to intestine |
Intestine | Primary site of nutrient absorption |
Liver | Accessory digestive organ that produces digestive compounds and detoxifies many constituents of the absorbed digested compounds |
Kidneys | Paired, flattened excretory organs that filter nitrogenous wastes from the blood |