Beckon heart
From Wikipedia, the free encyclopedia
| Anatomy | |
|---|---|
| Part of | Beckon bulb |
| System | Circulatory |
| Rate | One beat every 2–5 minutes |
| Present in | All four Beckon species |
The heart of a Beckon is the largest organ in its bulb. It drives the circulation of the whole organism, from the bulb down through the trunk into the root mat and back. It beats once every two to five minutes, and each beat travels out through the mat as a wave of contraction in its vessels. The pulse can be felt and heard on infested ground.
Structure
The heart is a muscular sac in the lower part of the bulb, above the top of the spine. In a 30-metre Adapted Beckon it is about the size of a large barrel. It pumps blood into vessels that run down inside the spine to the root crown, where they branch into the mat; the returning blood rises through a second set of vessels in the spine.
Circulation
The vessels inside the spine are rigid. The rising and falling columns of blood balance each other's weight, and the heart works only against friction, not against the height of the trunk. The vessels at the base of a large Beckon still carry the full pressure of the column above them, about 5 bar at the foot of a 50-metre Beckon, which the spine supports.
From the root crown, blood passes into the mat, where its vessels connect to neighbouring Beckons and to Dispatchers. The vessels of the mat contract in waves timed to the heartbeat. The rhythm resembles the shuttle streaming of slime moulds, which has a period of one to two minutes.
Blood
Beckon blood is dark, with a faint glow in the colour of the organism's hive. It carries oxygen, nutrients, the sulfate and fluoride used by the gas glands, and heat.
The pulse
On infested ground the pulse can be felt through the soles of boots and heard as a low thump at intervals of minutes. Its strength falls off with distance from the Beckon, and field teams use geophones to locate buried root mat and Beckons hidden by terrain. A pulse that slows or stops is a sign that the Beckon above it is dying.
Damage
Cutting the main vessels in the trunk lowers the pressure of the blood reaching the bulb and starves its organs of oxygen. In an Earth Beckon this is often fatal. A wound to the heart itself kills the Beckon. Its tissue dies, the walls of its gas cells begin to leak, and over several days it sags.