Thursday 20 June 2024

Malevolent Designer - A Newly-Discovered Fish Parasite

Red-lipped Blenny.
Credit to Matthew Hoelscher.
Previously uncharacterized parasite uncovered in fish worldwide

Parasites present creationists with an insurmountable problem, especially those who equate the putative designer with the Abrahamic, supposedly omnibenevolent, god of the Bible, Torah and Qur'an.

It is a problem for creationism because there is no way the design of parasites, which appear to have only two functions - Making their hosts sick, so increasing the suffering in the world, and producing more parasites to make more hosts sick - can't possibly be the work of an omnibenevolent designer, and the inevitable resulting arms races between parasite and host are not the act of an intelligent designer.

The traditional explanation offered by creationists, particularly those with only a rudimentary grasp of the subject is to blame 'devolution' [sic] caused by 'genetic entropy' which was made possible by 'Sin' following the mythical 'Fall' as an organism evolves away from some assumed initial perfection at 'creation'. Apart from betraying the religious fundamentalism dressed in a grubby lab coat, that is 'intelligent design' creationism, this is scientifically nonsensical and counter factual, of course.

The fact is that parasites are often highly adapted to live inside their hosts, and this is only possible in terms of evolution. A mutation which enhances a parasite’s ability to infect and live inside a host can't rationally be presented as less perfect than what went before. For it to spread through a species gene pool, it must convey an advantage, or at least be neutral allowing genetic drift. Detrimental mutations are quickly removed from the species gene pool by the assortative process of natural selection.

And now creationism's problems in this respect just got a lot bigger because an international team of researchers led by scientists at the Rosenstiel School of Marine, Atmospheric, and Earth Science of the University of Miami, the Institute of Evolutionary Biology (IBE), a joint centre of the Spanish National Research Council (CSIC) and the Pompeu Fabra University (UPF) has characterized a new parasite in the red-lipped blenny, a fish that lives in tropical reefs.

The international team has also revealed this parasite, an Ichthyocolid, is present in fish around the world.

What information do you have on the evolutionary origins and hosts of the Apicomplexa parasites, particularly the Ichthyocolids? The Apicomplexa is a large phylum of parasitic protozoa, which includes several important pathogens such as Plasmodium (the cause of malaria), Toxoplasma, and Cryptosporidium. These parasites are characterized by a unique structure called the apical complex, which they use to invade host cells. Here is an overview of the evolutionary origins and hosts of Apicomplexa, with a particular focus on Ichthyocolids:

Evolutionary Origins of Apicomplexa
  1. Origins and Phylogeny:
    • Apicomplexa belong to the larger group known as Alveolata, which also includes dinoflagellates and ciliates.
    • It is believed that Apicomplexa evolved from free-living photosynthetic ancestors related to the dinoflagellates. This hypothesis is supported by the presence of a relict plastid (apicoplast) in many Apicomplexa, which is thought to be derived from a photosynthetic algal ancestor through secondary endosymbiosis.
    • Molecular phylogenetic studies suggest that the common ancestor of Apicomplexa lost its photosynthetic ability and adopted a parasitic lifestyle.
  2. Adaptation to Parasitism:
    • The transition from a free-living to a parasitic lifestyle involved significant evolutionary changes. The development of the apical complex allowed these organisms to invade host cells efficiently.
    • The apicoplast, while non-photosynthetic, retains essential functions such as fatty acid synthesis, which are vital for the parasite's survival and proliferation within the host.

Hosts of Apicomplexa
  1. Diverse Range of Hosts:
    • Apicomplexa parasites infect a wide range of hosts, including vertebrates, invertebrates, and even other protozoa.
    • The host range includes humans, livestock, birds, fish, reptiles, amphibians, and various invertebrates such as insects and mollusks.
  2. Life Cycle:
    • Many Apicomplexa have complex life cycles involving multiple stages and often multiple hosts. For example, Plasmodium species have a life cycle that includes both a mosquito vector and a vertebrate host.

  1. Specific Group within Apicomplexa:
    • Ichthyocolids are a lesser-known group within the Apicomplexa, primarily parasitizing fish.
    • They are particularly significant in the context of aquaculture, where they can cause disease outbreaks and economic losses.
  2. Host Specificity and Infection:
    • Ichthyocolids exhibit a range of host specificities. Some species are highly specific, infecting only certain fish hosts, while others have a broader host range.
    • These parasites typically infect the gastrointestinal tract of their fish hosts but can also invade other tissues.
  3. Impact on Fish Hosts:
    • Infection by Ichthyocolids can lead to various health issues in fish, including reduced growth, poor condition, and increased mortality.
    • Understanding the life cycle and transmission dynamics of Ichthyocolids is crucial for managing infections in aquaculture settings.
Research and Challenges
  1. Research Gaps:
    • Compared to other apicomplexan parasites like Plasmodium and Toxoplasma, Ichthyocolids are less well-studied. This is partly due to their lower impact on human health but significant impact on aquaculture.
  2. Genomic Studies:
    • Advances in genomic and transcriptomic technologies are beginning to shed light on the biology and evolution of Ichthyocolids. These studies are essential for developing effective control measures against these parasites.
  3. Control and Management:
    • Effective control of Ichthyocolid infections in aquaculture involves a combination of good management practices, environmental control, and, in some cases, chemotherapeutic interventions.
Understanding the evolutionary origins and host interactions of Apicomplexa, particularly Ichthyocolids, is crucial for developing strategies to manage and control the diseases they cause. Ongoing research into their biology, life cycles, and host-parasite interactions will continue to provide valuable insights into these important parasites.
The parasite, a single-celled eukaryote, is from the group known as the Apicoplexa, so named because they all have a special complex structure at one end of their single cell, the apicoplast, which helps them gain access to their hosts. This structure is a relic of a plastid, betraying the fact that the Apicoplexa themselves were once free-living dinoflagellates that had formed a symbiotic relationship with a photosynthetic alga.

The Apicoplexa include pathogens which infect many species including humans, and include Plasmodium several species of which cause malaria, Toxoplasma, and Cryptosporidium. Fortunately, the newly characterised species seems to be restricted to fish hosts.

The team's findings are the subject of a research paper in the Cell Press journal Current Biology and of a news release from the Institute of Evolutionary Biology (IBE):
Previously uncharacterized parasite uncovered in fish worldwide

An international study led by the Institute of Evolutionary Biology (IBE) and the Rosenstiel School of Marine, Atmospheric, and Earth Science at the University of Miami has detected a parasite present world-wide in many marine fish.

This organism belongs to the apicomplexans, one of the most important groups of parasites at a clinical level. However, it had gone unnoticed in previous studies.

The parasite is geographically and taxonomically widespread in fish species around the planet, with potential implications for commercial fishing and oceanic food webs.

The ocean houses a vast mosaic of life beneath its surface, where millions of relationships are woven between its inhabitants every day. As they glide through the immensity of its waters, fish and other animals interact with a myriad of microscopic organisms. Some of them will integrate into their bodies, nourishing the food chain in the incessant cycle of life. Through their genetic information, we can detect many of these microbial symbionts in the blood of their hosts. However, they can go unnoticed if you're not looking for them.

Now an international research led by the Institute of Evolutionary Biology (IBE), a joint centre of the Spanish National Research Council (CSIC) and the Pompeu Fabra University (UPF), and the Rosenstiel School of Marine, Atmospheric, and Earth Science of the University of Miami has characterized a new parasite in the red-lipped blenny, a fish that lives in tropical reefs. The international team has also revealed its presence in fish around the world.

Published by Current Biology, the research used an innovative method to reconstruct part of the parasite's genome from sequencing data obtained from its host, and be able to detect its presence in other fish using genetic “barcodes” (DNA barcoding).

An "invisible" parasite has been unveiled
Despite its presence in fish worldwide, the parasite has not been properly characterized until now. The genomic data of the study reveals that this parasite belongs to a group of organisms previously uncharacterized and have been named ichthyocolids, from the Latin “fish dweller”.

Red-lipped Blenny.

Credit to Philippe Guillaume. CC BY 2.0 DEED

Although it had been previously identified by microscopy, we had not been able to separate the genomic signal from the host fish and the parasite until now. For the first time, we have been able to identify them through their DNA, and place them within the well-known group of apicomplexan parasites.

Javier del Campo, corresponding author
Department of Marine Biology and Ecology
Rosenstiel School of Marine, Atmospheric and Earth Science
University of Miami, Miami, FL, USA. And Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra)
Pg. Marítim de la Barceloneta, Barcelona, Catalonia, Spain.

The parasite is present in fish around the world

Beyond allowing the description of an entirely new group of apicomplexans, the genome reconstruction has allowed researchers to identify a series of genes that can be used to detect the presence of this organism in other genomic or microbiome samples as if it was a “barcode”.

Once we found ichthyocolids in the red-lipped blenny, a tropical fish, we wondered if it would also be part of the microbiota of other fish.

Anthony M. Bonacolta, first author
Department of Marine Biology and Ecology
Rosenstiel School of Marine, Atmospheric and Earth Science
University of Miami, Miami, FL, USA. And Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra)
Pg. Marítim de la Barceloneta, Barcelona, Catalonia, Spain.

The team compared the DNA of these apicomplexans with public databases of the microbiomes of hundreds of species of freshwater and marine fish. The results showed that these parasites appear associated with the majority of marine fish species analyzed and are present in all oceans. It would therefore be one of the most widespread parasites among marine fish, with potential implications for commercial fishing and oceanic food webs.

Future studies could help us better understand the impact of parasites as prevalent as ichthyocolids in marine ecosystems.

Javier del Campo.

A new member of apicomplexan parasites

The Ichthyocolids belong to Apicomplexa, a great group of parasites including the ones that cause Malaria and Toxoplasmosis. Some of them also parasite other mammals, birds or corals, and don’t commonly pose direct risk to human health. However, they are still important to study for the health of the oceanic ecosystems and for more context on the evolution of those human parasites.

The discovery of the ichthyocolids adds more context to this evolution. For the first time, they are placed as a sister group to well-known coral inhabitants, the corallicolids, also recently described as apicomplexans.

Studying ichthyocolids not only reveals more about the evolution of major parasites, but also the other basic traits of apicomplexans which may be important in a clinical sense. They may use similar infection mechanisms (as they are also a blood parasite) or have other similar biology which can enlighten our understanding of the biology of other apicomplexans.

Anthony M. Bonacolta.
Reference article
Anthony M. Bonacolta, Joana Krause-Massaguer, Nico J. Smit, Paul C. Sikkel, & Javier del Campo (2024).
A new and widespread group of fish apicomplexan parasites.
Current Biology. DOI:
Sadly, the main part of the paper in Current Biology is behind a paywall, so only the abstract is freely available:
Graphical abstract
  • Ichthyocolids represent a new group of fish-infecting apicomplexans.
  • Ichthyocolids are the sister group to the coral-infecting corallicolids.
  • Ichthyocolids lack chlorophyll-biosynthesis genes in their chloroplasts.
  • Ichthyocolids are geographically and taxonomically widespread in fish species.

Apicomplexans are obligate intracellular parasites that have evolved from a free-living, phototrophic ancestor. They have been reported from marine environmental samples in high numbers,1 with several clades of apicomplexan-related lineages (ARLs) having been described from environmental sequencing data (16S rRNA gene metabarcoding).2 The most notable of these are the corallicolids (previously ARL-V), which possess chlorophyll-biosynthesis genes in their relic chloroplast (apicoplast) and are geographically widespread and abundant symbionts of anthozoans.3 Corallicolids are related to the Eimeriorina, a suborder of apicomplexan coccidians that include other notable members such as Toxoplasma gondii.4 Ophioblennius macclurei, the redlip blenny, along with other tropical reef fishes, is known to be infected by Haemogregarina-like and Haemohormidium-like parasites5 supposedly belonging to the Adeleorina; however, phylogenetics shows that these parasites are instead related to the Eimeriorina.6,7 Hybrid genomic sequencing of apicomplexan-infected O. macclurei blood recovered the entire rRNA operon of this apicomplexan parasite along with the complete mitochondrion and apicoplast genomes. Phylogenetic analyses using this new genomic information consistently place these fish-infecting apicomplexans, hereby informally named ichthyocolids, sister to the corallicolids within Coccidia. The apicoplast genome did not contain chlorophyll biosynthesis genes, providing evidence for another independent loss of this pathway within Apicomplexa. Based on the 16S rRNA gene found in the apicoplast, this group corresponds to the previously described ARL-VI. Screening of fish microbiome studies using the plastid 16S rRNA gene shows these parasites to be geographically and taxonomically widespread in fish species across the globe with implications for commercial fisheries and oceanic food webs.

To summarise then, a single-celled eukaryote formed a symbiotic relationship with a marine alga which gave it the advantage of being able to photosynthesis sugar from water, carbon dioxide and sunlight. It then gave up photosynthesising and became a parasite on a whole range of other organisms and the remnants of the alga became the apical complex to help it gain access to its hosts.

Then, after a further period of evolution the Apicomplexa have diversified and specialised so each now had a range of hosts it could parasitise, with the Plasmodia becoming the parasites that cause malaria, Cryptosporidia and Toxoplasma causing other diseases and the Ichthyocolids becoming parasites on fish, making them sick and affecting the growth and health of fish and reducing fish stocks. And that probably only tells part of the story...

Creationists regard this ludicrously over-complex way to increase the suffering in the world as an example of intelligent design by an omnibenevolent god and reject the idea that it could be the unplanned consequence of a natural evolutionary process in which no gods, good, bad or indifferent, were involved.


The Unintelligent Designer: Refuting The Intelligent Design Hoax

ID is not a problem for science; rather science is a problem for ID. This book shows why. It exposes the fallacy of Intelligent Design by showing that, when examined in detail, biological systems are anything but intelligently designed. They show no signs of a plan and are quite ludicrously complex for whatever can be described as a purpose. The Intelligent Design movement relies on almost total ignorance of biological science and seemingly limitless credulity in its target marks. Its only real appeal appears to be to those who find science too difficult or too much trouble to learn yet want their opinions to be regarded as at least as important as those of scientists and experts in their fields.

Available in Hardcover, Paperback or ebook for Kindle


The Malevolent Designer: Why Nature's God is Not Good

This book presents the reader with multiple examples of why, even if we accept Creationism's putative intelligent designer, any such entity can only be regarded as malevolent, designing ever-more ingenious ways to make life difficult for living things, including humans, for no other reason than the sheer pleasure of doing so. This putative creator has also given other creatures much better things like immune systems, eyesight and ability to regenerate limbs that it could have given to all its creation, including humans, but chose not to. This book will leave creationists with the dilemma of explaining why evolution by natural selection is the only plausible explanation for so many nasty little parasites that doesn't leave their creator looking like an ingenious, sadistic, misanthropic, malevolence finding ever more ways to increase pain and suffering in the world, and not the omnibenevolent, maximally good god that Creationists of all Abrahamic religions believe created everything. As with a previous book by this author, "The Unintelligent Designer: Refuting the Intelligent Design Hoax", this book comprehensively refutes any notion of intelligent design by anything resembling a loving, intelligent and maximally good god. Such evil could not exist in a universe created by such a god. Evil exists, therefore a maximally good, all-knowing, all-loving god does not.

Illustrated by Catherine Webber-Hounslow.

Available in Hardcover, Paperback or ebook for Kindle


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