Bloodletting by the freshwater leech Hirudo medicinalis
is used to control swelling subsequent to the reattachment of
severed fingers or transplanted tissue. Saliva of bloodsucking
leeches contains the anticoagulant hirudin as well as an anesthetic.
This leech harbors a symbiotic bacterium Aeromonas
hydrophila; not only does the bacterium digest blood, but also
produces an antibiotic that kills other bacteria.
Burrowing polychaetes turn over 1900 tons of seafloor sand
per acre each year. Charles Darwin calculated that earthworms
bring 18 tons of soil to the surface per acre each year. Suction by
a muscular pharynx draws soil into the earthworm mouth. Food
is passed through the esophagus by the peristaltic movements of
digestive tract muscles to a crop, where the food is temporarily
stored. The muscular gizzard of the earthworm grinds seeds,
eggs, larvae, small animals, and plants ingested with soil. Annelids’
longitudinal and circular body-wall muscles work against
the coelomic fluid, which is, like all fluids, relatively incompressible;
this system functions as a hydraulic skeleton. Thin peritoneal
sheets called septa separate adjacent segments. As body-wall
muscles contract, colorless coelomic fluid flows from segment
to segment through openings in each septum. Food is pushed
through the gut from mouth to anus by cilia or by peristaltic
contractions of muscles that encircle the digestive tract. The
aquatic annelid pumps water through its burrow with peristaltic
body waves, cilia, and parapodia. The water current brings in
food and dissolved oxygen and removes waste.
Bloodletting by the freshwater leech Hirudo medicinalis
is used to control swelling subsequent to the reattachment of
severed fingers or transplanted tissue. Saliva of bloodsucking
leeches contains the anticoagulant hirudin as well as an anesthetic.
This leech harbors a symbiotic bacterium Aeromonas
hydrophila; not only does the bacterium digest blood, but also
produces an antibiotic that kills other bacteria.
Burrowing polychaetes turn over 1900 tons of seafloor sand
per acre each year. Charles Darwin calculated that earthworms
bring 18 tons of soil to the surface per acre each year. Suction by
a muscular pharynx draws soil into the earthworm mouth. Food
is passed through the esophagus by the peristaltic movements of
digestive tract muscles to a crop, where the food is temporarily
stored. The muscular gizzard of the earthworm grinds seeds,
eggs, larvae, small animals, and plants ingested with soil. Annelids’
longitudinal and circular body-wall muscles work against
the coelomic fluid, which is, like all fluids, relatively incompressible;
this system functions as a hydraulic skeleton. Thin peritoneal
sheets called septa separate adjacent segments. As body-wall
muscles contract, colorless coelomic fluid flows from segment
to segment through openings in each septum. Food is pushed
through the gut from mouth to anus by cilia or by peristaltic
contractions of muscles that encircle the digestive tract. The
aquatic annelid pumps water through its burrow with peristaltic
body waves, cilia, and parapodia. The water current brings in
food and dissolved oxygen and removes waste.
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