can someone describe it?
2007-05-02 12:31:20 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Biology
It's been a few years since I taught earthworms, but...
An earthworm has three blastic layers (triploblast). These are the endoderm (lining the digestive tract), ectoderm (lining the outside of the organism) and mesoderm (everything in between, including glandular systems and circulatory organs).
If you think of the outer body of an earthworm as being a tube, then the digestive tract is a narrower tube running through the outer one, and the two are separated by a tissue layer.
The endoderm evolved into what we call the alimentary canal (from mouth to anus). The mesoderm, in humans, develops into all the internal organ systems -- heart, lungs, ancillary digestive organs. The ectoderm became all the nerves, muscles, skeleton and skin tissues.
All the animals that evolved from Annelids (the chordates: fishes, amphibians, reptiles, birds, and mammals) share this basic body plan (which is why we study the earthworm). Right up to and including us humans, we are all just a tube within a tube.
(And that's probably way more than you needed, huh?)
2007-05-02 13:24:46 · answer #1 · answered by Clint 3 · 0⤊ 0⤋
Define Body Tube
2016-10-31 06:21:12 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The earthworm is a coelomate, that is an animal with a body cavity. More primitive animals like the flatworms have no body cavity. This body cavity gives room for the internal organs to move, expand and contract with ease. It also acts as a hydrostatic skeleton giving the worm some rigidity since it lacks a true skeleton. The alimentary canal (digestive tube) runs down the center of the cavity. The cavity offers protection to these organs as it moves from place to place.
2007-05-02 13:18:09 · answer #3 · answered by ATP-Man 7 · 1⤊ 0⤋
This just means that the earthworm's body is long like a tube, and the digestive system is an inside tube going from the head end to the tail end.
2007-05-02 12:34:27 · answer #4 · answered by ecolink 7 · 1⤊ 0⤋
This Site Might Help You.
RE:
describe the tube-within tube body structure of the earthworm?
can someone describe it?
2015-08-20 08:24:43 · answer #5 · answered by ? 1 · 0⤊ 0⤋
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2016-03-14 06:35:43 · answer #6 · answered by Anonymous · 0⤊ 0⤋