Groove-like tracks on the ocean floor made by giant deep-sea single-celled organisms could lead to new insights into the evolutionary origin of animals.
Biologist Mikhail “Misha” Matz from The University of Texas at Austin and his colleagues, including Dr. Tamara Frank with the Center for Ocean Exploration and Deep-Sea Research, Harbor Branch Oceanographic Institute (HBOI) at Florida Atlantic University, recently discovered grape-sized protists and their complex tracks on the ocean floor near the Bahamas. This is the first time a single-celled organism has been shown to make such animal-like traces. The team’s discovery was recently published online in Current Biology and will also appear in the journal’s December 9 print issue.
The finding is significant, because similar fossil grooves and furrows found from the Precambrian era, as early as 1.8 billion years ago, have always been attributed to early evolving multi-cellular animals.“If our giant protists were alive 600 million years ago and the track was fossilized, a paleontologist unearthing it today would without a shade of doubt attribute it to a kind of large, multi-cellular, bilaterally symmetrical animal,” said Matz, an assistant professor of integrative biology. “We now have to rethink the fossil record.”
The National Oceanographic and Atmospheric Administration’s (NOAA) Office of Ocean Exploration and Research provided several years of significant interdisciplinary funding to the research group involved in this discovery (Operation Deep-Scope 2004, 2005, 2007). The NOAA program provided funds for the scientists to explore unknown or little studied regions of the deep-sea floor using HBOI’s Johnson-Sea-Link (JSL) submersible. The JSL provided a nearly 180 degree unimpeded field of view making it possible for the scientists to see the vast field of “grapes” and their tracks during this expedition.
“The unique collecting tools available on the Johnson-Sea-Link allowed us to gather intact specimens from the sea floor at a depth of 750 meters so that Mikhail could analyze them in his laboratory,” said Frank. “It was a ‘eureka’ moment when he realized that these specimens were giant mobile protists and not fecal pellets as we originally suspected.”
Most animals, from humans to insects, are bilaterally symmetrical, meaning that they can be roughly divided into halves that are mirror images. The bilateral animals, or “Bilateria,” appeared in the fossil record in the early Cambrian about 542 million years ago, quickly diversifying into all of the major animal groups, or phyla, still alive today. This rapid diversification, known as the Cambrian explosion, puzzled Charles Darwin and remains one of the biggest questions in animal evolution to this day. Very few fossils exist of organisms that could be the Precambrian ancestors of bilateral animals, and even those are highly controversial. Fossil traces are the most accepted evidence of the existence of these proto-animals.
“We used to think that it takes bilateral symmetry to move in one direction across the seafloor and thereby leave a track,” said Matz. “You have to have a belly and a backside and a front and back end. Now, we show that protists can leave traces of comparable complexity and with a very similar profile.”
With their find, Matz, Frank and their colleagues argue that fossil traces cannot be used alone as evidence that multi-cellular animals were evolving during the Precambrian, slowly setting the stage for the Cambrian explosion. “I personally think now that the whole Precambrian may have been exclusively the reign of protists,” said Matz. “Our observations open up this possible way of interpreting the Precambrian fossil record.”
Matz says the appearance of all the animal body plans during the Cambrian explosion might not just be an artifact of the fossil record. There are likely other mechanisms that explain the burst-like origin of diverse multi-cellular life forms. DNA analysis confirmed that the giant protist found by Matz and his colleagues in the Bahamas is Gromia sphaerica, a species previously known only from the Arabian Sea.
They did not observe the giant protists in action, and Matz says they likely move very slowly. The sediments on the ocean floor at their particular location are very stable and there are no current—perfect conditions for the preservation of tracks. Matz says the protists probably move by sending leg-like extensions, called pseudopodia, out of their cells in all directions. The pseudopodia then grab onto mud in one direction and the organism rolls that way, leaving a track. He aims to return to the location in the future to observe their movement and investigate other tracks in the area.
Matz says the giant protists’ bubble-like body design is probably one of the planet’s oldest macroscopic body designs, which may have existed for 1.8 billion years.
“Our guys may be the ultimate living fossils of the macroscopic world,” he said.
Florida Atlantic University opened its doors in 1964 as the fifth public university in Florida. Today, the University serves more than 26,000 undergraduate and graduate students on seven campuses strategically located along 150 miles of Florida's southeastern coastline. Building on its rich tradition as a teaching university, with a world-class faculty, FAU hosts ten colleges: College of Architecture, Urban & Public Affairs, Dorothy F. Schmidt College of Arts & Letters, the Charles E. Schmidt College of Biomedical Science, the Barry Kaye College of Business, the College of Education, the College of Engineering & Computer Science, the Harriet L. Wilkes Honors College, the Graduate College, the Christine E. Lynn College of Nursing and the Charles E. Schmidt College of Science.
Gisele Galoustian | Newswise Science News
Further reports about: > Animal > Bilateral > Cambrian > Cambrian explosion > Groove-like tracks > JSL > Johnson-Sea-Link > Oceanographic > Pacific Ocean > Precambrian > animal evolution > giant deep-sea single-celled > giant protists > multi-cellular > ocean floor > organism > protist > sea floor > traces
Historical rainfall levels are significant in carbon emissions from soil
30.05.2017 | University of Texas at Austin
3D printer inks from the woods
30.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Scientists have developed a new method of characterizing graphene’s properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials. Researchers from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics reported their findings in the journal Physical Review Applied.
Graphene consists of a single layer of carbon atoms. It is transparent, harder than diamond and stronger than steel, yet flexible, and a significantly better...
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
30.05.2017 | Life Sciences
30.05.2017 | Life Sciences
30.05.2017 | Physics and Astronomy