Marine Flatworms

Author(s):  
Leslie Newman ◽  
Lester Cannon

Marine Flatworms provides a fascinating introduction to the intriguing world of polyclad flatworms, a group of large, free-living marine Platyhelminthes, which are found throughout the world but are most colourful in tropical waters. Although not related to molluscs, they are often mistaken for sea slugs because of their brilliant colour patterns. Written in an accessible style by two leading experts in the field, this book explores flatworms’ unusual structure, feeding habits, their curious reproductive behaviour (including ‘penis fencing’), their mimicry and toxicology. With a foreword by Professor Reinhardt Kristensen of the Copenhagen Zoological Museum, Marine Flatworms is the first comprehensive guide to polyclad families and genera. It contains more than 300 colour photographs from every part of the world.

Zoosymposia ◽  
2021 ◽  
Vol 20 ◽  
Author(s):  
LIANA JOHANN ◽  
GUILHERME LIBERATO DA SILVA

The family Tydeidae consists of small, free-living, soft-bodied mites with a diversity of feeding habits, including phytophages, pollen feeders and even predators, but the majority are scavengers or fungivores. Approximately 330 species in 30 genera have been described from throughout the world, but only a few species (<1% of all species) have been studied for their life history. This review provides a survey of their life history with a focus on their lifespan.


Author(s):  
W. L. Steffens ◽  
Nancy B. Roberts ◽  
J. M. Bowen

The canine heartworm is a common and serious nematode parasite of domestic dogs in many parts of the world. Although nematode neuroanatomy is fairly well documented, the emphasis has been on sensory anatomy and primarily in free-living soil species and ascarids. Lee and Miller reported on the muscular anatomy in the heartworm, but provided little insight into the peripheral nervous system or myoneural relationships. The classical fine-structural description of nematode muscle innervation is Rosenbluth's earlier work in Ascaris. Since the pharmacological effects of some nematacides currently being developed are neuromuscular in nature, a better understanding of heartworm myoneural anatomy, particularly in reference to the synaptic region is warranted.


Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1634
Author(s):  
Tatiana Carolina Gomes Dutra de Souza ◽  
Danielle Gava ◽  
Rejane Schaefer ◽  
Raquel Arruda Leme ◽  
Gisele da Silva Porto ◽  
...  

Porcine circovirus 3 (PCV-3) was identified in domestic pigs worldwide. Although PCV-3 has also been detected in wild boars, information regarding its circulation in this free-living animal species is scarce. To investigate PCV-3 occurrence in free-living wild boars in Brazil, 70 serum samples collected between January 2017 and June 2019 in Paraná state, Brazil were analyzed by PCR assay. Amplicons measuring 330 bp in length were amplified in seven (10.0%) of the serum samples and confirmed to be PCV3-specific by nucleotide (nt) sequencing. As the amplified products from the serum samples yielded only intermediate levels of viral DNA, lung samples from the seven PCR-positive wild boars were also evaluated by PCR. Of these samples, five lung samples were positive and provided high levels of viral DNA. The three lung samples that presented the highest levels of viral DNA were selected for amplification and sequencing of the whole PCV-3 genome. The three full-length sequences obtained were grouped in PCV-3 clade “a”, and the sequences exhibited 100% nucleotide similarity among them. The PCV-3 field strains of this study showed nucleotide and amino acid similarities of 98.5–99.8% and 98.8–100%, respectively, with whole-genome PCV-3 sequences from around the world.


Evolution ◽  
1974 ◽  
Vol 28 (3) ◽  
pp. 337 ◽  
Author(s):  
John L. Cisne
Keyword(s):  

2021 ◽  
pp. 185-215
Author(s):  
Nabil Majdi ◽  
Tom Moens ◽  
Walter Traunspurger

Abstract This chapter provides overview of the feeding habits and food sources of aquatic nematodes. The environmental constraints on feeding, food recognition, and feeding selectivity are also addressed, together with the complex, indirect trophic interactions between nematodes and their microbial prey. To raise awareness of the inherent methodological and/or interpretational problems in studies of nematode feeding ecology, the chapter ends with a brief look at the methods that have been adapted to quantify feeding rates in nematodes.


Zootaxa ◽  
2020 ◽  
Vol 4816 (3) ◽  
pp. 392-396
Author(s):  
DAIZY BHARTI ◽  
FRANCISCO BRUSA ◽  
SANTOSH KUMAR ◽  
KAILASH CHANDRA

Catenulida are mostly inhabitants of freshwater ecosystems, like ponds, streams, though the marine species are few (Larsson and Willems, 2010). About 110 species of catenulids are known worldwide, with most of the studies conducted in South America (Marcus, 1945a, 1945b; Noreña et al., 2005), North America (Kepner and Carter 1931; Nuttycombe and Waters, 1938) and Scandinavian Peninsula (Luther, 1960, Larsson and Willems, 2010; Larsson et al., 2008). The diversity of catenulids from India has not been studied intensively; however some reports on other turbellaria exists for the country (Annandale, 1912; Whitehouse, 1913; Kapadia, 1947; Basil and Fernando, 1975; Apte and Pitale, 2011; Kalita and Goswami, 2012; Venkataraman et al., 2015). The genus Stenostomum, however, has been studied extensively around the world with identification of over 60 species (Tyler et al., 2006-2016). This is first report of the genus from India. The present study was part of the project to catalogue the diversity of free living protozoan ciliates from the Hooghly stretch of the Ganga River during which the flatworms were found. The worms were studied based on the live observations, with recognition of characters which led to its identification. This study serves to fill knowledge gap in the freshwater flatworms from India. 


Author(s):  
J. Llewellyn

Gastrocotyle trachuri and Pseudaxine trachuri infect young Trachurus trachurus at Plymouth as soon as the 3- or 4-month-old adolescent fishes descend to the sea bottom in October. The parasites normally mature in 3 or 4 months, but, exceptionally, in about 1 month, and the life-span is normally no longer than 1 year. Trachurus specimens at the beginning of their second year pick up a largely new infection of parasites.G. trachuri and P. trachuri are much less frequent on 2- and 3-year-old specimens of Trachurus and probably occur only very rarely on still older fishes, the limiting factor being not an age-immunity but a post-spawning migration of the host from the concentration of free-living infective stages of the parasites in coastal waters.The parasites have adapted themselves to a seasonal change in the feeding habits of Trachurus by ceasing to produce larvae in anticipation of the summer disappearance of scad from the sea bottom in pursuit of pelagic food-organisms.


Parasitology ◽  
1953 ◽  
Vol 43 (1-2) ◽  
pp. 102-109 ◽  
Author(s):  
J. M. Watson

An investigation of the occurrence of helminthic intestinal parasites in the population of central and southern Iraq led to the discovery that human trichostrongylosis is relatively common in man along the banks of the Shatt-al-Arab and the lower course of the Tigris and Euphrates rivers. In the Basrah area the incidence is 25·4% and at Nasriyah 14·2% but it falls rapidly along the northward course of the rivers and is absent in the centre and north of the country. This is correlated with the occurrence of heavy shade cast by palm forest, high humidity due to the presence of perennial swamps, and the occurrence of grass and other carpet plants in the south; which jointly provide the conditions necessary for the development and survival of the free-living stages ofTrichostrongylus.Hookworm (Ancylostoma duodenale) is more evenly distributed over the area and is common farther north where conditions are more arid; owing to the fact that the free-living stages can develop under much drier conditions than those ofTrichostrongylus, probably mainly on moist defaecation sites near irrigation channels.The species ofTrichostrongylusinvolved is not known but is probablyT. colubriformiswhich is common locally in sheep and has been found in man at Abadan by Marsh (1949). Infection is presumably contracted by ingestion of greenstuff carrying infective juveniles.Since infections are light, symptoms minimal and treatment ineffective care should be taken to differentiate trichostrongylosis from ancylostomiasis in order that no unnecessary medication be undertaken.The world incidence of human trichostrongylosis is higher than was formerly believed. The available reports are reviewed, and it is concluded that not less than fifty million persons harbour this worm throughout the globe.


2019 ◽  
Vol 20 (2) ◽  
pp. 326
Author(s):  
ELENA DESIDERÀ ◽  
LUANA MAGNANI ◽  
AUGUSTO NAVONE ◽  
PAOLO GUIDETTI ◽  
CARLOTTA MAZZOLDI

This study describes the first ever reported direct observation of a pair spawning event and the reproductive liveries of the white grouper, Epinephelus aeneus. Spawning took place on a rocky bank located in the Marine Protected Area (MPA) of Tavolara-Punta Coda Cavallo (NE Sardinia, Italy), in the Western Mediterranean Sea. In the evening of August 4th, 2018, the spawning of two large-sized individuals (~90 cm total length), displaying distinct colour patterns, was observed using SCUBA diving. This direct observation is the first record of E. aeneus male reproductive livery, characterized by a darker coloration on the head, the dorsal part of the body and the caudal fin. In addition, information on the environmental conditions in which reproduction occurred was collected. At the study site, relatively high seawater temperatures were recorded at the time of the E. aeneus spawning (24 °C at 24.7 m), as well as over the 2018 summer months (July-September), even in deep waters (>35 m), compared to previous summers. The spawning event occurred in a coralligenous-dominated seascape where fishing is prohibited, while diving activities are allowed. The site hosts abundant populations of ecologically and commercially valuable fish species (e.g., groupers, sparid fishes), with significant proportions of large-sized individuals (i.e. reproducers). Further studies are needed to advance our knowledge of the white grouper, with a particular emphasis on reproduction and the importance of implementing effective protection measures. Prioritizing management actions at key reproductive sites, such as rocky banks, is essential for ensuring the protection and/or recovery of over-exploited species. 


2021 ◽  
Author(s):  
Erwan Delrieu-Trottin ◽  
Hans Hartmann Salvo ◽  
Pablo Saenz Agudelo ◽  
Mauricio F. Landaeta ◽  
Alejandro Pérez Matus

AbstractThe blenniids of the genus Scartichthys represent key herbivore species of central and south American Pacific coastal reefs. Yet Scartichthys spp. remain difficult to identify in the field, especially across the c.a 6000 km where three of the four currently accepted species are known to occur in sympatry. The main diagnostic characters from traditional taxonomy that have been used to revise this genus are indeed elusive. At the same time, species can display multiple colour patterns in the field, depending on the ontogenetic stage, habitat association, and/or reproductive behaviour. Overall, molecular characterization is warranted to help address these issues. Here, we used a combination of colouration, morphological and molecular data for the first time, including specimens representative of the four currently valid species and seven described colour patterns. Our integrative approach revealed that only three of the four species should be considered as valid; Scartichthys gigas (Steindachner, 1876), S. variolatus (Valenciennes, 1836) and S. viridis (Valenciennes, 1836); while S. crapulatus Williams 1990 should be synonymized with S. viridis. In the same way, our analyses show that one of the colour patterns attributed so far to S. gigas is characteristic of the juvenile stages of S. viridis. Our time-calibrated phylogeny shows that this genus is relatively young, with an estimated time of divergence between Scartichthys gigas and S. viridis of around 1.71 Ma. In comparison, the Desventuradas and Juan Fernandez Islands endemic S. variolatus diverged about 1.95 Ma. Our results help to clarify the taxonomy of the Scartichthys genus.


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