Lamprey is mostly marine as well as fresh water.
Metamorphosis in Lamprey 1. They are most common in the European river system. The marine form of sea-lamprey P.
Two distinct phases are present in the life-history of lampreys. They spend major part of their adult life in sea and are provided with a suctorial mouth. The larval phase, the Ammocoetes lives in fresh water and feed on microscopic food trapped in endostyle.
External Features of Lamprey: The head and trunk are nearly cylindrical and the tail is laterally compressed Fig. The smooth, slimy body surface is devoid of scales. The upper surface, is usually dark and the lower surface white. A median dorsal fin divided into two unequal parts and a caudal fin continuous with posterior dorsal fin are present.
A single median nostril and the pineal organ; closely behind it are present on the dorsal surface of the head. At the anterior end a large downwardly directed basin-like depression, the buccal funnel is present Fig.
Radiating rows of yellow, homy teeth on cartilaginous pads are present in the buccal funnel. A prominence, the tongue bearing large, horny teeth projects from the bottom of the buccal funnel. The narrow mouth lies just above the tongue.
Gill slits or gill pores are seven pairs of small openings on the sides of the head. The anus, a narrow opening lies in a small depression, the vent on the ventral surface at the junction of trunk and tail.
Body Wall and Muscles of Lamprey: The skin is soft. The epidermis bears numerous mucus secreting unicellular glands.
In addition to these, two other types of secretory cells are present: A layer of collagen fibres form the cutis beneath the epidermis. The pigment cells are star-shaped and change their position under different conditions of illumination, imparting change of colour from pallid to dusky and vice versa.
The muscles of the trunk and the tail are arranged in myotomes in a zigzag course. Since the waves are short, progress by swimming is slow. The skeleton is wholly cartilaginous. The notochord, ill-developed skull and branchial basket constitute axial skeleton.
The notochord Fig; In the caudal region the rods fuse to form a single plate bearing foramina for the spinal nerves and sends processes to the base of the fin. The cranium is primitive. The floor is occupied by a basal plate formed by paired parachordals and trabeculae.
An incomplete box enclosing the brain and special sense organs is formed by pieces of cartilage attached to the basal plate Fig. A large aperture, die basicranial fontanelle is present in front of the cranium.
The roof of the cranium is made of membranous fibrocartilage, supported by a transverse bar. Auditory capsules are united with the posterior end of die basal plate and form the end of the neurocranium. The olfactory capsule is an imperfectly paired concavo- convex plate, supporting the posterior wall of the olfactory sac.
Fibrous tissue joins the capsule with the cranium. A sub-ocular arch extends downward and outward from each side of the nasal plate to support the eye Fig.
A slender styloid process hangs from the sub ocular arch and a small cornual cartilage is connected to its lower end. The skeleton of the buccal funnel and branchial basket are attached to the cranium. A ring-like annular cartilage supports the buccal funnel.Difference # Lamprey (Petromyzon): 1.
Lamprey is mostly marine as well as fresh water. 2. It has both parasitic and nonparasitic species. Difference between Lamprey and Hagfish | Animal Kingdom.
Development is indirect with ammocoete (larva), metamorphosis is present in lamprey. Difference # Hagfish (Myxine): 1. Hagfish is . Brian K. Hall - The Neural Crest and Neural Crest Cells in Vertebrate Development and Evolution (Springer series in solid-state sciences) ().
Note that g mole Kr The atomic weights of elements are listed in the periodic table. molecular weight = g mole-I). 50 EXERCISE 5 Each of these solutions contains the .
Discovery of fossil lamprey larva from the Lower Cretaceous reveals its three-phased life cycle Article (PDF Available) in Proceedings of the National Academy of Sciences (43) · October How to Write a Scientific Paper or Laboratory Report XXIII.
and elude a pursuer. you allude to a book. If you're interested in learn~ ing more about improving your writing." Council of Biology Editors style manual: A guide for authors. keep it simple and straightforward. read The Elements of Style (4th ed. Mar 01, · This study reports on tight junction-associated MARVEL proteins of larval sea lamprey (Petromyzon marinus) and their potential role in ammocoete osmoregulation.
Two occludin isoforms (designated Ocln and Ocln-a) and a tricellulin (Tric) were identified.