Within the phylum nematoda, there
have been many adaptations that parasitic worms in plants and animals
have gone through in order to keep evolving. Looking more specifically
at Dirofilaria immitis, there have been a couple main adaptations
that have helped it to evolve. One of the adaptations is the
pseudocoelom, which is also found in other nematodes. Pseudocoelomates
have a body cavity that is partially lined with mesoderm. The coelom
creates a space for circulation and internal organs. Dirofilaria
immitis, along with other nematodes, move not with limbs or fins,
rather a hydrostatic skeleton. The hydrostatic skeleton is a fluid
filled chamber that allows the organism to move by changing the shape of
the fluid filled cavity. Coordinated muscle contractions allow one side
of the muscles to contract, thus changing the shape of the fluid filled
chamber and allowing the nematode to bend and move. This is an
excellent way to move without having to expend a lot of energy.
Every organism must have a way to
sense things and react to certain stimuli in their environment. Being a
nematode, Dirofilaria immitis has a dorsal nerve cord that runs
from the nerve ganglion, the central point where all the nerves come
together, to almost the posterior end of the worm. Dirofilaria
immitis uses the nerve ganglion and the dorsal nerve cord as a
sensory organ to find food and give the organism direction as to where
it is in its environment.
was taken from Wikipedia.org and was released into the public domain by
its author Josh Grosse.
Another very important adaptation in
Dirofilaria immitis deals with how it makes its energy
anaerobically. In collaborative research done on the identification and
analysis of genes expressed in the adult Dirofilaria immitis,
researchers proposed that, “adult heartworm likely adapted an anaerobic
electron transfer-based energy generation system distinct from the
aerobic pathway utilized by its mammalian host (Yin 2006).
Although these are only a couple of
the many important adaptations nematodes, more specifically
Dirofilaria immitis, have expressed, it is important to remember
that species are always evolving over time in accordance with Darwin’s
theory on evolution.