Detection Of European Strain Of Echinococcus Multilocularis In North America, Emily J. Jenkins, Andrew S. Peregrine, Janet E. Hill, Christopher Somers, Karen Gesy, Brian Barnes, Bruno Gottstein, Lydden Polley

Harold W. Manter Laboratory of Parasitology: Library Materials

To the Editor: In 2009, an alveolar hydatid cyst, the intermediate stage of the cestode Echinococcus multilocularis, was detected in the liver of a dog from Quesnel, British Columbia (BC), Canada, 600 km west of the nearest known record of this parasite in central North America. Alveolar hydatid cysts normally occur in rodent intermediate hosts. However, humans can serve as aberrant intermediate hosts; cysts generally originate in the liver and, in about one third of cases, metastasize throughout the body. Detection of the larval stage of this pathogen in an unusual host in a new geographic region required application …

The Origin Of Malarial Parasites In Orangutans, M. Andreína Pacheco, Michael J.C. Reid, Michael A. Schillaci, Carl A. Lowenberger, Biruté M. F. Galdikas, Lisa Jones-Engel, Ananias A. Escalante

Harold W. Manter Laboratory of Parasitology: Library Materials

Background: Recent findings of Plasmodium in African apes have changed our perspectives on the evolution of malarial parasites in hominids. However, phylogenetic analyses of primate malarias are still missing information from Southeast Asian apes. In this study, we report molecular data for a malaria parasite lineage found in orangutans.

Methodology/Principal Findings: We screened twenty-four blood samples from Pongo pygmaeus (Kalimantan, Indonesia) for Plasmodium parasites by PCR. For all the malaria positive orangutan samples, parasite mitochondrial genomes (mtDNA) and two antigens: merozoite surface protein 1 42 kDa (MSP-1₄₂) and circumsporozoite protein gene (CSP) were amplified, cloned, and …

The Evolutionary Host Switches Of Polychromophilus: A Multi-Gene Phylogeny Of The Bat Malaria Genus Suggests A Second Invasion Of Mammals By A Haemosporidian Parasite, Fardo Witsenburg, Nicolas Salamin, Philippe Christe

Harold W. Manter Laboratory of Parasitology: Library Materials

Background: The majority of Haemosporida species infect birds or reptiles, but many important genera, including Plasmodium, infect mammals. Dipteran vectors shared by avian, reptilian and mammalian Haemosporida, suggest multiple invasions of Mammalia during haemosporidian evolution; yet, phylogenetic analyses have detected only a single invasion event. Until now, several important mammal-infecting genera have been absent in these analyses. This study focuses on the evolutionary origin of Polychromophilus, a unique malaria genus that only infects bats (Microchiroptera) and is transmitted by bat flies (Nycteribiidae).

Methods: Two species of Polychromophilus were obtained from wild bats caught in Switzerland. These …

Timing The Origin Of Human Malarias: The Lemur Puzzle, M. Andreína Pacheco, Fabia U. Battistuzzi, Randall E. Junge, Omar E. Cornejo, Cathy V. Williams, Irene Landau, Lydia Rabetafika, Georges Snounou, Lisa Jones-Engel, Ananias A. Escalante

Harold W. Manter Laboratory of Parasitology: Library Materials

Background: Timing the origin of human malarias has been a focus of great interest. Previous studies on the mitochondrial genome concluded that Plasmodium in primates, including those parasitic to humans, radiated relatively recently during a process where host switches were common. Those investigations, however, assumed constant rate of evolution and tightly bound (fixed) calibration points based on host fossils or host distribution. We investigate the effect of such assumptions using different molecular dating methods. We include parasites from Lemuroidea since their distribution provides an external validation to time estimates allowing us to disregard scenarios that cannot explain their introduction …

Rerooting The Evolutionary Tree Of Malaria Parasites, Diana C. Outlaw, Robert E. Ricklefs

Harold W. Manter Laboratory of Parasitology: Library Materials

Malaria parasites (Plasmodium spp.) have plagued humans for millennia. Less well known are related parasites (Haemosporida), with diverse life cycles and dipteran vectors that infect other vertebrates. Understanding the evolution of parasite life histories, including switches between hosts and vectors, depends on knowledge of evolutionary relationships among parasite lineages. In particular, inferences concerning time of origin and trait evolution require correct placement of the root of the evolutionary tree. Phylogenetic reconstructions of the diversification of malaria parasites from DNA sequences have suffered from uncertainty concerning outgroup taxa, limited taxon sampling, and selection on genes used to assess relationships. As …

Multi-Host Model-Based Identification Of Armillifer Agkistrodontis (Pentastomida), A New Zoonotic Parasite From China, Shao-Hong Chen, Qin Liu, Yong-Nian Zhang, Jia-Xu Chen, Hao Li, Ying Chen, Peter Steinmann, Xiao-Nong Zhou

Harold W. Manter Laboratory of Parasitology: Library Materials

Background: Pentastomiasis is a rare parasitic infection of humans. Pentastomids are dioecious obligate parasites requiring multiple hosts to complete their life cycle. Despite their worm-like appearance, they are commonly placed into a separate sub-class of the subphylum Crustacea, phylum Arthropoda. However, their systematic position is not uncontested and historically, they have been considered as a separate phylum.

Methodology/Principal Findings: An appraisal of Armillifer agkistrodontis was performed in terms of morphology and genetic identification after its lifecycle had been established in a multi-host model, that is, mice and rats as intermediate hosts, and snakes (Agkistrodon acutus and Python molurus) …

How Birds Combat Ectoparasites, Dale H. Clayton, Jennifer A. H. Koop, Christopher W. Harbison, Brett R. Moyer, Sarah E. Bush

Harold W. Manter Laboratory of Parasitology: Library Materials

Birds are plagued by an impressive diversity of ectoparasites, ranging from feather-feeding lice, to feather-degrading bacteria. Many of these ectoparasites have severe negative effects on host fitness. It is therefore not surprising that selection on birds has favored a variety of possible adaptations for dealing with ectoparasites. The functional significance of some of these defenses has been well documented. Others have barely been studied, much less tested rigorously. In this article we review the evidence--or lack thereof--for many of the purported mechanisms birds have for dealing with ectoparasites. We concentrate on features of the plumage and its components, as well …

Phylogenetic Position Of The Acariform Mites: Sensitivity To Homology Assessment Under Total Evidence, Almir R. Pepato, Carlos E. F. Da Rocha, Jason A. Dunlop

Harold W. Manter Laboratory of Parasitology: Library Materials

Background: Mites (Acari) have traditionally been treated as monophyletic, albeit composed of two major lineages: Acariformes and Parasitiformes. Yet recent studies based on morphology, molecular data, or combinations thereof, have increasingly drawn their monophyly into question. Furthermore, the usually basal (molecular) position of one or both mite lineages among the chelicerates is in conflict to their morphology, and to the widely accepted view that mites are close relatives of Ricinulei.

Results: The phylogenetic position of the acariform mites is examined through employing SSU, partial LSU sequences, and morphology from 91 chelicerate extant terminals (forty Acariformes). In a static homology framework, …

Genbank, Dennis A. Benson, Ilene Karasch-Mizrachi, David J. Lipman, James Ostell, Eric W. Sayers

Harold W. Manter Laboratory of Parasitology: Library Materials

GenBank(R) is a comprehensive database that contains publicly available nucleotide sequences for more than 380,000 organisms named at the genus level or lower, obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole genome shotgun (WGS) and environmental sampling projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and accession numbers are assigned by GenBank staff upon receipt. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through the NCBI Entrez retrieval system that integrates data …

Evolutionary History Of Mammalian Sucking Lice (Phthiraptera: Anoplura), Jessica E. Light, Vincent S. Smith, Julie M. Allen, Lance A. Durden, David L. Reed

Harold W. Manter Laboratory of Parasitology: Library Materials

Background

Sucking lice (Phthiraptera: Anoplura) are obligate, permanent ectoparasites of eutherian mammals, parasitizing members of 12 of the 29 recognized mammalian orders and approximately 20% of all mammalian species. These host specific, blood-sucking insects are morphologically adapted for life on mammals: they are wingless, dorso-ventrally flattened, possess tibio-tarsal claws for clinging to host hair, and have piercing mouthparts for feeding. Although there are more than 540 described species of Anoplura and despite the potential economical and medical implications of sucking louse infestations, this study represents the first attempt to examine higher-level anopluran relationships using molecular data. In this study, we …

Ancient Leishmaniasis In A Highland Desert Of Northern Chile, Maria Antonietta Costa, Carney Matheson, Lucia Iachetta, Otto Appenzeller

Harold W. Manter Laboratory of Parasitology: Library Materials

Background

Leishmaniasis is an infectious disease endemic today in many areas of South America.

Methodology

We discovered morphologic and molecular evidence of ancient infections in four female skulls in the archaeological cemetery of Coyo Oriente, in the desert of San Pedro de Atacama, northern Chile. The boney facial lesions visible in the skulls could have been caused by a number of chronic infections including chronic Leishmaniasis. This diagnosis was confirmed using PCR-sequenced analyses of bone fragments from the skulls of the affected individuals. Leishmaniasis is not normally found in the high-altitude desert of northern Chile; where the harsh climate does …

Taxonomic Information Exchange And Copyright: The Plazi Approach, Donat Agosti, Willi Egloff

Harold W. Manter Laboratory of Parasitology: Library Materials

Background

A large part of our knowledge on the world's species is recorded in the corpus of biodiversity literature with well over hundred million pages, and is represented in natural history collections estimated at 2–3 billion specimens. But this body of knowledge is almost entirely in paper-print form and is not directly accessible through the Internet. For the digitization of this literature, new territories have to be chartered in the fields of technical, legal and social issues that presently impede its advance. The taxonomic literature seems especially destined for such a transformation.

Discussion

Plazi was founded as an association with …

An Overview Of Systematics And Evolution Of Ticks, Santiago Nava, Alberto A. Guglielmone, Atilio J. Mangold

Harold W. Manter Laboratory of Parasitology: Library Materials

All species of ticks (Acari: Ixodida) are grouped into three families: Argasidae (186 species), Ixodidae (692 species), and Nuttalliellidae (monotypic). Molecular markers have been developed and applied for tick studies along with conventional techniques. The origin of ticks is during the pre-mid Cretaceous period (with both the Argasidae and Ixodidae being established in the middle Cretaceous). Primeval hosts were probably reptiles or amphibians. The Argasidae contains two to five subfamilies according to authors but relationships among its members are far from resolved. The Ixodidae were formed by the basal Prostriata group (genus Ixodes, subfamily Ixodinae) and the Metastriata group …

Canine Vector-Borne Diseases In Brazil [Review], Filipe Dantas-Torres

Harold W. Manter Laboratory of Parasitology: Library Materials

Canine vector-borne diseases (CVBDs) are highly prevalent in Brazil and represent a challenge to veterinarians and public health workers, since some diseases are of great zoonotic potential. Dogs are affected by many protozoa (e.g. Babesia vogeli, Leishmania infantum, and Trypanosoma cruzi), bacteria (e.g. Anaplasma platys and Ehrlichia canis), and helminths (e.g. Dirofilaria immitis and Dipylidium caninum) that are transmitted by a diverse range of arthropod vectors, including ticks, fleas, lice, triatomines, mosquitoes, tabanids, and phlebotomine sand flies. This article focuses on several aspects (etiology, transmission, distribution, prevalence, risk factors, diagnosis, control, prevention, and public health …

Spider Mite (Acari: Tetranychidae) Mitochondrial Coi Phylogeny Reviewed: Host Plant Relationships, Phylogeography, Reproductive Parasites And Barcoding, Vera I.D. Ros, Johannes A.J. Breeuwer

Harold W. Manter Laboratory of Parasitology: Library Materials

The past 15 years have witnessed a number of molecular studies that aimed to resolve issues of species delineation and phylogeny of mites in the family Tetranychidae. The central part of the mitochondrial COI region has frequently been used for investigating intra- and interspeciWc variation. All these studies combined yield an extensive database of sequence information of the family Tetranychidae. We assembled this information in a single alignment and performed an overall phylogenetic analysis. The resulting phylogeny shows that important patterns have been overlooked in previous studies, whereas others disappear. It also reveals that mistakes were made in submitting the …

Theileria Electrophori N.Sp., A Parasite Of The Electric Eel Electrophorus Electricus (Osteichthyes: Cypriniformes: Gymnotidae) From Amazonian Brazil, Ralph Lainson

Harold W. Manter Laboratory of Parasitology: Library Materials

The name Theileria electrophori n. sp. is proposed for a small parasite described in the erythrocytes of the electric eel, Electrophorus electricus, from Amazonian Brazil. Division of the organism in the erythrocyte produces only four bacilliform daughter cells which become scattered in the host cell, without a cruciform or rosette-shaped disposition. Exoerythrocytic meronts producing a large number of merozoites were encountered in Giemsa-stained impression smears of the internal organs, principally in the liver, and are presumably the source of the intraerythrocytic forms of the parasite. This developmental pattern is characteristic of piroplasms within the family Theileriidae, where the author …

Phylogenetic Approach To The Study Of Triatomines (Triatominae, Heteroptera) = Abordagem Filogenética Em Triatomíneos (Triatominae, Heteroptera), Ester Tartarotti, Maria Tercília Vilela De Azeredo-Oliveira, Carlos Roberto Ceron

Harold W. Manter Laboratory of Parasitology: Library Materials

Triatomines are insects belonging to the Hemiptera order, Heteroptera suborder, Reduviidae family and Triatominae subfamily. All members of this subfamily are hematophagous. Triatomines evolved from Reduviidae predators and they are probably polyphyletic in origin. The combination of anatomical, physiological and ethological factors observed in this group, as well as the plesiomorphic and apomorphic characters that differentiate the five tribes and fourteen triatomine genera reinforce the polyphiletic hypotesis. However if we consider the five groups of triatomines, the Rhodniini, Cavernicolini, Bolboderini, Linshcosteini and Alberproseniini tribes constitute monophyletic groups, while the Triatomini tribe is considered polyphyletic. The New World is the center …

Phylogenetic Approach To The Study Of Triatomines (Triatominae, Heteroptera) = Abordagem Filogenética Em Triatomíneos (Triatominae, Heteroptera), Ester Tartarotti, M. T. V. Azeredo-Oliveira, C. R. Ceron

Harold W. Manter Laboratory of Parasitology: Library Materials

Abstracts

Triatomines are insects belonging to the Hemiptera order, Heteroptera suborder, Reduviidae family and Triatominae subfamily. All members of this subfamily are hematophagous. Triatomines evolved from Reduviidae predators and they are probably polyphyletic in origin. The combination of anatomical, physiological and ethological factors observed in this group, as well as the plesiomorphic and apomorphic characters that differentiate the five tribes and fourteen triatomine genera reinforce the polyphiletic hypotesis. However if we consider the five groups of triatomines, the Rhodniini, Cavernicolini, Bolboderini, Linshcosteini and Alberproseniini tribes constitute monophyletic groups, while the Triatomini tribe is considered polyphyletic. The New World is the …

Myxozoan Genera: Definition And Notes On Taxonomy, Life-Cycle Terminology And Pathogenic Species, Jiří Lom, Iva Dyková

Harold W. Manter Laboratory of Parasitology: Library Materials

A list of myxozoan genera is presented in the current taxonomical scheme. These genera are defined; their type species and most important pathogens along with their hosts are listed. Simultaneously, definitions of actinospore stages representing sexual stages of the myxosporean life cycle are given; altogether, 17 actinospore collective groups with 180 types have been described. Life cycles of the two classes of the phylum Myxozoa, Malacosporea and Myxosporea, are briefly outlined with specification of the appropriate terms. Up to now, 4 malacosporean and 2,180 myxosporean species assigned to a total of 62 genera, have been established. The surviving classification of …

A Monkey’S Tale: The Origin Of Plasmodium Vivax As A Human Malaria Parasite, Ananias A. Escalante, Omar E. Cornejo, Denise E. Freeland, Amanda C. Poe, Ester Durrego, William E. Collins, Altaf A. Lal

Harold W. Manter Laboratory of Parasitology: Library Materials

The high prevalence of Duffy negativity (lack of the Duffy blood group antigen) among human populations in sub-Saharan Africa has been used to argue that Plasmodium vivax originated on that continent. Here, we investigate the phylogenetic relationships among 10 species of Plasmodium that infect primates by using three genes, two nuclear (β-tubulin and cell division cycle 2) and a gene from the plastid genome (the elongation factor Tu). We find compelling evidence that P. vivax is derived from a species that inhabited macaques in Southeast Asia. Specifically, those phylogenies that include P. vivax as an ancient lineage from …

Beyond Bloodletting: Fda Gives Leeches A Medical Makeover, Carol Rados

Harold W. Manter Laboratory of Parasitology: Library Materials

In June 2004, the Food and Drug Administration cleared the first application for leeches (Hirudo medicinalis) to be used in modern medicine as medical devices. By definition, a medical device is an article intended to diagnose, cure, treat, prevent, or mitigate a disease or condition, or to affect a function or structure of the body, that does not achieve its primary effect through a chemical action and is not metabolized.

Biosystematics And Evolution Of The Triatominae = Biossistemática E Evolução De Triatomíneos, Christopher J. Schofield

Harold W. Manter Laboratory of Parasitology: Library Materials

Abstract

In this paper we summarize the systematics of the 130 currently recognized species of Triatominae and the key features of their evolutionary background. There is increasing evidence that the subfamily has polyphyletic origins, with the various tribes and species groups probably arising from different reduviid lineages in relatively recent times.

Resumo

Neste trabalho resume-se a sistemática das 130 espécies de triatomíneos atualmente reconhecidas, com os elementos principais de sua evolução. Existem evidências crescentes para a origem polifilética da subfamília. As diferentes tribos e grupos de espécies que a compõem teriam surgido recentemente, a partir de diferentes linhagens de reduviídeos.

Recommendations From A Satellite Meeting (International Symposium To Commemorate The 90th Anniversary Of The Discovery Of Chagas Disease, April 11-16 1999, Rio De Janeiro, Brazil), Alejandro O. Luquetti, Aluízio Rosa Prata, Alvaro Moncayo, Alvaro Romanha, Ana Maria Jansen, Bianca Zingales, Carlos Morel, Carlos Ponce, Egler Chiari, Elisa Cupolillo, Elisa Ponce, Felipe Guhl, Hooman Momen, José Rodrigues Coura, Mario Steindel, Michael Miles, Michel Tibayrenc, Octavio Fernandes, Riva Oliveira, Rodrigo Zeledón, Sonia Gumes Andrade, Toby Vincent Barrett, Vanize Macêdo, Zigman Brener

Harold W. Manter Laboratory of Parasitology: Library Materials

During this symposium the standardization of the nomenclature of Trypanosoma cruzi strains was discussed, in a parallel session, with a view to facilitating the use and understanding of a common nomenclature that would serve not only taxonomists but the general community of researchers working with T. cruzi.

The diversity in the behavior and morphology of T. cruzi isolates was soon recognized after the discovery of Chagas disease. Since then a variety of biochemical and molecular techniques have revealed the great genetic diversity present in strains of this parasite. Different investigators have described this diversity by using various …

The Evolution Of Primate Malaria Parasites Based On The Gene Encoding Cytochrome B From The Linear Mitochondrial Genome, Ananias A. Escalante, Denise E. Freeland, William E. Collins, Altaf A. Lal

Harold W. Manter Laboratory of Parasitology: Library Materials

We report a phylogenetic analysis of primate malaria parasites based on the gene encoding the cytochrome b protein from the mitochondrial genome. We have studied 17 species of Plasmodium, including 14 parasitic in primates. In our analysis, four species were used for rooting the Plasmodium phylogenetic tree: two from closely related genera (Hepatocystis sp. and Haemoproteus columbae) and two other Apicomplexa (Toxoplasma gondii and Theileria parva). We found that primate malaria parasites form a monophyletic group, with the only exception being the Plasmodium falciparum–Plasmodium reichenowi lineage. Phylogenetic analyses that include two species …

Genetic Polymorphism Among Cryptosporidium Parvum Isolates: Evidence Of Two Distinct Human Transmission Cycles, Michael M. Peng, Lihua Xiao, Amanda R. Freeman, Michael J. Arrowood, Ananias A. Escalante, André C. Weltman, Corinne S.L. Ong, William R. Mac Kenzie, Altaf A. Lal, Charles B. Beard

Harold W. Manter Laboratory of Parasitology: Library Materials

We report the results of molecular analysis of 39 isolates of Cryptosporidium parvum from human and bovine sources in nine human outbreaks and from bovine sources from a wide geographic distribution. All 39 isolates could be divided into either of two genotypes, on the basis of genetic polymorphism observed at the thrombospondin-related adhesion protein (TRAP-C2) locus. Genotype 1 was observed only in isolates from humans. Genotype 2, however, was seen in calf isolates and in isolates from a subset of human patients who reported direct exposure to infected cattle or consumed items thought to be contaminated with cattle feces. Furthermore, …

Evolutionary Origin Of Plasmodium And Other Apicomplexa Based On Rrna Genes, Ananias A. Escalante, Francisco J. Ayala

Harold W. Manter Laboratory of Parasitology: Library Materials

We have explored the evolutionary history of the Apicomplexa and two related protistan phyla, Dinozoa and Ciliophora, by comparing the nucleotide sequences of small subunit ribosomal RNA genes. We conclude that the Plasmodium lineage, to which the malarial parasites belong, diverged from other apicomplexan lineages (piroplasmids and coccidians) several hundred million years ago, perhaps even before the Cambrian. The Plasmodium radiation, which gave rise to several species parasitic to humans, occurred 129 million years ago; Plasmodium parasitism of humans has independently arisen several times. The origin of apicomplexans (Plasmodium), dinoflagellates, and ciliates may be >1 billion years old, …

Phylogeny Of The Malarial Genus Plasmodium, Derived From Rrna Gene Sequences, Ananias A. Escalante, Francisco J. Ayala

Harold W. Manter Laboratory of Parasitology: Library Materials

Malaria is among mankind's worst scourges, affecting many millions of people, particularly in the tropics. Human malaria is caused by several species of Plasmodium, a parasitic protozoan. We analyze the small subunit rRNA gene sequences of 11 Plasmodium species, including three parasitic to humans, to infer their evolutionary relationships. Plasmodium falciparum, the most virulent of the human species, is closely related to Plasmodium reiehenowi, which is parasitic to chimpanzee. The estimated time of divergence of these two Plasmodium species is consistent with the time of divergence (6-10 million years ago) between the human and chimpanzee lineages. The …

Human Anisakis Transmitted By Marine Food Products: Raw Facts On Sushi And Sashimi, Thomas L. Deardorff, Stephen G. Kayes, Takakazu Fukumura

Harold W. Manter Laboratory of Parasitology: Library Materials

A seafood connection with parasitic diseases in Hawaii clearly has been established and clinicians and physicians need to become more aware of this association. The risk of people in Hawaii becoming infected with these parasites from seafood products are extremely low; however, this risk increases slightly if imported fresh fishes raw or partially cooked are eaten. Prevention of these diseases, therefore, is probably best accomplished by providing continuous, accurate, and responsible information to the public concerning the health risks of eating raw fishery products; by advising the seafood industry of potential problems and methods of addressing them properly; and by …

Plasmodium Falciparum Appears To Have Arisen As A Result Of Lateral Transfer Between Avian And Human Hosts, A. P. Waters, D. G. Higgins, T. F. Mccutchan

Harold W. Manter Laboratory of Parasitology: Library Materials

It has been proposed that the acquisition of Plasmodium falciparum by man is a relatively recent event and that the sustained presence of this disease in man is unlikely to have been possible prior to the establishment of agriculture. To establish phylogenetic relationships among the Plasmodum species and to unravel the mystery of the orign of P. fakiparum, we have analyzed and compared phylogenetically the small-subunit ribosomal RNA gene sequences of the species of malaria that infect humans as well as a number of those sequences from species that infect animals. Although this comparison confirmed the three established …

Molecular Evidence For Inclusion On The Phylum Pentastomida In The Crustacea, Lawrence G. Abele, Won Kim, Bruce E. Felgenhauer

Harold W. Manter Laboratory of Parasitology: Library Materials

The phylogenetic status of the phylum Pentastomida (tongue worms) was considered on the basis of comparison of nucleotide sequences of 18S ribosomal RNA from the pentastome Porocephalus crotali, the branchiuran crustacean fish louse Argulus nobilis, other crustaceans, and representatives of the Annelida, Chelicerata, Myriapoda, and Insecta. Maximum parsimony and invariants (at P < 0.04) analyses support an Argulus/Porocephalus clade, providing strong support for the proposal that tongue worms are highly modified crustaceans closely related to fish lice.