The outbreak of the emerging coronavirus, "SARS Cove 2" - which caused severe panic among humans and caused the pandemic of the "Covid-19" disease - led to a reconsideration of the relationship between the parasite and its host blatantly, and the disruption that parasites can cause both human society and systems. Environmental.
Although parasites are common in modern environmental systems, we actually know little about parasitism in the distant past, and we do not know when parasites first developed, and researchers have long sought a better understanding of the evolutionary importance of parasites to help reduce their impact.
But research published in the journal Nature Communications on June 2 brought us a great step closer to understanding, as the oldest known historical example of the parasite’s relationship to the host has been documented.
The Chinese research team - which cooperated with researchers from Sweden and Australia - emphasized that its findings represent the first statistically supported example of parasites from the early Cambrian period (period 541 million years to 485 million years).
The first parasites
The detected fossil parasites are worms that lived about 515 million years ago, intruding on primitive oysters, and are considered to be "the first known parasites" to date.
Fossil oysters are brachialis, a division of marine animals that has solid shells on the upper and lower sides, and has been known from the Cambrian period until now.
Brackets erect planktonic legs by pushing water currents towards their shells openings, and this allows them to filter and filter food particles, but the helminths intercept some of this food for themselves.
"The chiropods covered with tubes outside their shells were much smaller than others, and the tubes were aligned with the feeding currents of this type of oyster," said study author and paleontologist Chevy Chang of the Northwest Chinese University.
"The parasite was a parasite that reduced its host's fitness by stealing its food," Zhang said.
Worms and their host appeared shortly after the "Cambrian explosion" that began about 540 million years ago during the Cambrian period, when all major animal groups appeared in the fossil record.
In this age, the small-legged humeriels, which resembled small oysters, were very abundant, as they numbered more than 12 thousand species at that time, but today they represent only 450 species.
A rare find
The researchers discovered that the hardened tubes covering the surface of fossil shells were helminths, after they were able to determine a clear negative effect on the host, as the parts that grew without parasites appeared larger than those in parasites.
"Our analyzes show that the organisms that live in the tubes directly influence the biological fitness of the host, which supports the assertion that they are parasitic rather than being reciprocal or symmetrical with brachiioles," the team said.
Depending on the direction of the tubes, the researchers found that the worms were parasites of the "kleptop" type that "intrude theft", a form of nutrition, in which an animal takes another food that was caught, collected, or otherwise prepared by another animal.
This discovery is rare, as it is difficult to document parasitic reactions in the fossil record, because most inferences must be made based on appearance.
the importance of studying
Intrusion is usually defined as a continuous relationship, as one of the organisms - the parasite - increases its success, by exploiting another object known as the host.
There are clear examples of fossil parasites, and the impressive discoveries of parasites in the fossil record include bacteria with a spiral shape roughly identical to that causing Lyme disease, and they were discovered inside a 15-million-year-old fossil tick.
Fossils provide clear evidence of evolutionary and environmental change, but evidence of direct interaction between fossil organisms is unlikely to be preserved. It is often difficult to prove that a suspected fossil parasite was actually exploiting a host, because parasites often degrade very quickly, Hence the importance of this study, which documents the oldest known example of the parasite’s relationship to the host.