natures vampire: the lamprey

Natures Vampire: The Lamprey

By Rachel, Paige and Jenn

Life ProcessSpawning Phase: Spring -early summerOnce sea lampreys have reached sexual maturity, they stop feeding and begin to congregate off the mouths of streams and rivers in preparation for spawning.

Lampreys construct crescent-shaped nests of small stones and gravel. The female may lay 30,000 to 100,000 eggs. After spawning, the adults die.

Larval Phase: Most fertilized eggs settle in amongst the gravel of the nest and hatch in a few weeks. The young larvae emerge from the nest and then burrow into the stream's sand and silt bottom. The larvae feed on algae, detritus, and various small organisms.

Transforming Phase: Late summer- early fallAfter three or more years as harmless larvae, they undergo a change called transformation, where they develop eyes and a sucker-like mouth with sharp teeth.

Parasitic Phase: Lampreys typically move into the sea to begin a parasitic life, attaching to a fish by their mouths and feeding on the blood and tissues of the host They can spend 12-18 months in the parasitic phase until they are sexually mature enough to reproduce.

Diet/Nutrition

Larva Phase: algae, detritus and various small organisms

Parasitic Phase: feed off host (fish)One lamprey can consume over 40 pounds of fish in its lifetime

Spawning phase: No feeding

Specialized Systems

• Digestive• Circulatory• Nervous• Excretory• Reproductive• Motile? yes

Digestive System

Mouth →Pharynx→ Esophagus → Intestines

• Alimentary canal: runs from mouth to the anus. • No stomach • Intestines: The site of the emulsification, digestion and

absorption of nutrients. • The latter portion of the intestine digests bacteria, reabsorbs

water and forms feces. • The last section of the intestine narrows to form an exit called

the anus. The resulting solid wastes leave the body at this point.

Digestive System

Nervous system

• Lamprey's have a primitive vertebrate nervous system, meaning the brain structure is fairly simple compared to other vertebrate animals

• System consists of the brain and a hollow spinal cord– Situated above the alimentary canal. – Vertebrate nerve cord and brain contain a cerebrospinal fluid which

contains mineral salts and traces of protein and sugar. The fluid helps to support the nervous tissue and probably plays some part in its nutrition.

• The nerve fibers are not covered by the myelin sheath (a fatty insulating layer) found in all higher vertebrates– Therefore nervous conduction is slow. The complex nervous connections

found in higher forms are impossible in these early vertebrates.

Nervous System

Lamprey Brain

Circulatory/Respiratory Systems• Blood flows through a series of vessels to supply oxygen and nutrients

to the body and to remove carbon dioxide and other wastes. – Arteries and arterioles carry blood away from the heart– Veins and venules carry blood back towards the heart– Capillaries are the smallest vessels where the gases are exchanged with the

cells of the body• A lamprey “breathes” by extracting the oxygen present in the water in

which it lives• Water: mouth →pharynx → respiratory tube • Within the respiratory tube are seven gill pouches, each containing the

finer feather-like gill lamellae. The gill lamellae increase the surface area of the respiratory structures and contain the small capillary beds that extract oxygen.

Circulatory/Respiratory Systems

• Problem: When a lamprey is feeding and attached to a fish the mouth serves as an attachment function, it is no longer available for use in respiration.

• Solution: Water can be drawn directly into the respiratory tube through the external gill slits. Muscular contractions change the volume of the respiratory tube and thus control the movement of water over the gill lamellae.

Circulatory/Respiratory SystemsLamprey larva

Excretory System

• Kidney: filters out waste from the blood– Ions, water and other nitrogenous wastes– Responsible for maintaining osmoregulation

• The balance between the salts in the body and the salts in the environment.

• Freshwater: kidneys excrete extremely dilute urine to maintain the ionic balance in the body.

• Salt water: kidneys excretes a highly concentrated urine. Lampreys rely on the gills to rid the body of excess salt.

Reproductive System

• In late winter, the lamprey's sexual reproductive system grows and their intestines shrink

• Therefore, they don't eat in the winter but live off stored fat

Female Reproductive System

Larva Body Plan

toothless

Rudimentary eyes

Body Plan

The mouth is a round, sucking opening with teeth

2 eyes1 nostril on top of head

Dorsal fin

Tail fin

7 gill openings on each side of the body

Range from 15 to 100 centimeters (6 to 40 inches) long

Lack bones, jaws, scales and paired fins

Symmetry: bilateral

Internal Plan

Ecological Niche- Chordata

• Environments:• The sea lamprey is indigenous to the

Atlantic and Pacific Oceans and returns to freshwater tributaries to spawn.

• Found in the Great Lakes • Role in environment: parasite, vertebrae • Relationships: Parasitic/dependent upon host

Challenge: Considered a pest

Lamprey’s can kill large numbers of predatory sport fish. People notice the lack of large fish and the scars on others. The lamprey invasion made it hard on the people who fished the Great Lakes to make a living.

Evolutionary History• Of the 46,000 known species of

vertebrates, lampreys and hagfish are the only surviving jawless vertebrates.

• Lampreys are the most “primitive” of the vertebrates, meaning that they are the least altered from the first vertebrates.– They lack jaws, paired pectoral and pelvic fins,

and scales.• “Apart from being the oldest fossil lamprey

yet discovered, [these fossils] show that lampreys have been parasitic for at least 360 million years”. - Dr. Bruce Rubidge

Lamprey vs. Hagfish

Bibliography

• http://www.truaxbiology.com/sully/Sully_Bio/Chordates_files/Sea%20Lamprey.pdf

• http://www.daviddarling.info/encyclopedia/V/vertebrate_nervous_system.html

• http://www.allsands.com/science/animals/sealampreysgui_skg_gn.htm