The plankton and the benthos: origins and early history of an evolving relationship

Paleobiology ◽  
1994 ◽  
Vol 20 (3) ◽  
pp. 297-319 ◽  
Author(s):  
Philip W. Signor ◽  
Geerat J. Vermeij
Keyword(s):  
Benthic Communities ◽  
Marine Species ◽  
Suspension Feeding ◽  
Marine Animals ◽  
Suspension Feeders ◽  
Larval Stages ◽  
Large Numbers ◽  
Ultimate Cause ◽  
Marine Realm ◽  
History Of

Modern marine plankton communities include a broad diversity of metazoans that are suspension-feeding or micropredatory as adults. Many benthic marine species have larval stages that reside, and often feed, in the plankton for brief to very long periods of time, and most marine benthic communities include large numbers of suspension-feeders. This has not always been the case. Cambrian benthic communities included relatively few suspension-feeders. Similarly, there were few metazoan clades represented in the plankton, either as adult suspension-feeders or as larvae. Review of the fossil record suggests that the diversification of the plankton and suspension-feeding marine animals began in the Late Cambrian and continued into the Ordovician. These changes were accompanied by, and probably influenced, concurrent major changes in the marine realm, including an increase in tiering within benthic communities, the replacement of the Cambrian fauna by the Paleozoic fauna, and a general taxonomic diversification. The ultimate cause of these changes is uncertain, but it appears likely that the plankton was and is a refuge from predation and bioturbation for adults and larvae alike. The expansion in plankton biomass thus provided increased ecological opportunities for suspension-feeders in the plankton and benthos.

scholarly journals The biology of Limacina retroversa

1954 ◽  
Vol 33 (2) ◽  
pp. 297-312 ◽  
Author(s):  
J. E. Morton
Keyword(s):  
Life History ◽  
Breeding Season ◽  
Detailed Account ◽  
Larval Stages ◽  
Large Numbers ◽  
History Of ◽  
Clione Limacina

The Plymouth Fauna List contains records of two genera of pteropods, Limacina and Clione. Of the first, Limacina retroversa (Flem.) is by far the better-known species, apparently occurring regularly at Plymouth in large numbers in townettings from outside, and sometimes inside, the Sound. It breeds at Plymouth from June to August, and Lebour (1932) has given a detailed account of its breeding and larval stages and has discussed its role in the plankton. The second species of Limacina at Plymouth is lesueuri (d'Orbigny), which has been observed from time to time since 1906, when it was very common. The last record in the Fauna is off the Breakwater in 1920. Of the gymnosomatous pteropods, Clione limacina Phipps is the only species regularly occurring. Lebour (1931) has described the life history of this form, and mentions February to August as its months of greatest abundance. Its breeding season is June to August. Another gymnosome, tentatively referred to as Clionina longicauda, is reported by Russell (1936), and from the specimen department at Plymouth Laboratory the writer obtained some preserved specimens, not easily identifiable, of a Pneumodermopsis taken locally; its species is perhaps ciliata, recorded by Massy (1917) from the Irish Coast.

LABORATORY STUDIES ON THE TOXICITY OF INSECTICIDES TO THE BERTHA ARMYWORM (MAMESTRA CONFIGURATA) (LEPIDOPTERA: NOCTUIDAE)

1975 ◽  
Vol 107 (8) ◽  
pp. 865-872 ◽  
Author(s):  
C. R. Harris ◽  
S.A. Turnbull
Keyword(s):  
Direct Contact ◽  
Developmental Stages ◽  
Contact Toxicity ◽  
Mamestra Configurata ◽  
Larval Stages ◽  
Large Numbers ◽  
Third Stage ◽  
History Of ◽  
Dual Objectives ◽  
Bertha Armyworm

AbstractThis study had dual objectives: to select a series of insecticides toxic to the bertha armyworm, Mamestra configurata (Walk.), and to determine susceptibility of the various developmental stages to insecticides. Pupae were collected from infested rapeseed fields in Alberta and a laboratory rearing procedure suitable for production of large numbers of insects was devised. The direct contact toxicity of 50 insecticides to third-stage larvae was assessed. Methomyl and DDT were included as standard insecticides. None of the experimental insecticides was as toxic as methomyl but about one half were more toxic than DDT. Tests with representative organochlorine, organophosphorus, and carbamate insecticides indicated that all caused rapid knockdown of third-stage larvae. There was no evidence of subsequent recovery. After the life history of the bertha armyworm under controlled environmental conditions was determined, tests were conducted to ascertain the susceptibility of the various developmental stages to methomyl, chlorpyrifos, leptophos, and methidathion. Eggs and first and second stage larvae were more susceptible to direct contact applications of the insecticides than were the later larval stages, pupae, and adults.

The developmental history of Mutela bourguignati (Ancey) Bourguignat (Mollusca: Bivalvia)

1961 ◽  
Vol 244 (711) ◽  
pp. 259-298 ◽  
Keyword(s):  
Ventral Surface ◽  
Main Body ◽  
South American ◽  
Freshwater Bivalve ◽  
Byssus Thread ◽  
Larval Stages ◽  
Large Numbers ◽  
History Of ◽  
And Function ◽  
First Time

An account is given for the first time of the development of Mutela bourguignati (Ancey) Bourguignat, an African freshwater bivalve of the family Mutelidae. Eggs are shed in large numbers into the inner demibranchs. There they develop into minute larvae similar in some respects to the lasidium larvae of certain South American freshwater mussels, but differing in several ways. Each larva consists of a rounded body covered dorsally and laterally by a thin pellicle and provided anteriorly with two lobes clothed with cilia. Posteriorly, and on the ventral surface, are two sets of minute hooks. Anteriorly is a remarkable elongate, flaccid and colourless tentacle more than seventy times as long as the larva itself. There is no gut, nor can endodermal or mesodermal tissues be recognized as such at this stage. After liberation via the exhalant siphon these larvae settle on the cyprinid fish Barbus altianalis radcliffi and there metamorphose and begin a parasitic phase of development. The larval pellicle folds, and its opposed edges fuse so as completely to enclose the larva. Two tubular outgrowths grow from its anterior end into the superficial tissues of the fish and serve both as organs of attachment and nutrition. In their vicinity skeletal tissues of the host are broken down. The main body of the larva, now designated the haustorial larva, elongates and becomes differentiated into a stalk and a bud. The stalk protrudes from the fish and bears the bud clear of the host. Within the bud the adult bivalve eventually develops. The stalk is traversed by long prolongations of the mantle which run into the haustorial tubes and function as absorptive tissues. The cuticle is not calcified nor is it composed of conchiolin. As differentiation proceeds the definitive mantle, which is the lineal descendant of the larval mantle, begins to secrete first periostracum then calcareous matter to form the rudiments of the valves, and a rudiment of the ligament is also formed. As adult features gradually appear the bud is burst and a young bivalve, little more than 1 mm in length, attached to a long stalk emerges. Independent, particulate feeding commences at this stage. Rupture of both cuticular and mantle elements eventually takes place at the point of juncture of stalk and young bivalve and the latter falls away to begin an independent existence. At the time of release it is capable of active locomotion and is able to produce a slender byssus thread. A detailed, illustrated account of these changes, both external and internal, is given, and the development of certain individual organs is traced. The nature of the cuticle of the haustorial larva, the effect of this larva on its host, and the affinities and probable evolution of the larval stages are discussed, and the importance of taking larval development into account in classification is emphasized.

Capture of conspecific planktonic larvae by the suspension-feeding gastropod Crepipatella peruviana: association between adult and larval size

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
G A Rivera-Figueroa ◽  
J A Büchner-Miranda ◽  
L P Salas-Yanquin ◽  
J A Montory ◽  
V M Cubillos ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Larval Mortality ◽  
Feeding Preference ◽  
The Other ◽  
Suspension Feeding ◽  
Adult Size ◽  
Free Living ◽  
Larval Size ◽  
Suspension Feeders ◽  
Planktonic Larvae

ABSTRACT Free-living, planktonic larvae can be vulnerable to capture and ingestion by adult suspension-feeders. This is particularly the case for larvae that settle gregariously in benthic environments where suspension-feeders occur at high densities. Larvae of gregarious suspension-feeding species are at particularly high risk, as adults of their own species often serve as cues for metamorphosis. We conducted laboratory experiments to assess the extent to which adults of the suspension-feeding caenogastropod Crepipatella peruviana would capture and ingest their own larvae. Experiments were conducted with adults of different sizes, with larvae of different ages and sizes, and in the presence or absence of phytoplankton. Adults captured larvae in all experiments. The presence of microalgae in the water did not influence the extent of larval capture. On average, 39% of larvae were captured during the 3-h feeding periods, regardless of adult size. However, up to 34% of the larvae that were captured on the gill were later discarded as pseudofaeces; the other 64% were ingested. The extent of capture by adults was not related to adult size, or to larval size and, thus, to larval age. Our results suggest that the filtration of congeneric larvae by adult C. peruviana is a result of accidental capture rather than a deliberate feeding preference. Such ingestion could, however, still be an important source of larval mortality, especially when the advanced larvae of this species are searching for a suitable substrate for metamorphosis.

Studies on the life-history of Bunostomum phlebotomum (Railliet, 1900), a hookworm parasite of cattle

Parasitology ◽  
1946 ◽  
Vol 37 (3-4) ◽  
pp. 192-201 ◽  
Author(s):  
J. F. A. Sprent
Keyword(s):  
Infective Larva ◽  
Stage Larva ◽  
Fourth Stage ◽  
Larval Stages ◽  
The Third ◽  
Third Stage ◽  
History Of ◽  
Time Required ◽  
Cutaneous Blood ◽  
Fourth Stage Larva

A description is given of the processes of copulation, formation of the egg and spermatozoon, cleavage, embryogeny and hatching in B. phlebotomum. These processes were found to be essentially similar to those in other strongyle nematodes.The anatomy of the first three larval stages is described and the observations of Conradi & Barnette (1908) and Schwartz (1924) were largely confirmed.Penetration of the skin of calves by the infective larva was observed histologically. The larvae were found to have reached the dermis within 30 min. and to have penetrated the cutaneous blood vessels within 60 min. of application to the skin. The larvae were found in the lung where the third ecdysis was in progress 10 days after penetration of the skin. A description is given of the growth of the third-stage larva in the lung, the changes which take place during the third ecdysis, and the anatomy of the fourth-stage larva.The fourth-stage larvae exsheath in the lungs and travel to the intestine. After a period of growth in which sexual differentiation takes place, the fourth ecdysis occurs and the adult parasite emerges. The time required for the attainment of maturity was found to be somewhere between 30 and 56 days after penetration of the skin.This paper was written at the Ministry of Agriculture and Fisheries Veterinary Laboratories, Wey-bridge, and the writer would like to express his gratitude to the Director, Prof. T. Dalling, also to Dr W. R. Wooldridge, chairman of the Council of the Veterinary Educational Trust for their help and encouragement. The writer's thanks are also due to Dr H. A. Baylis, Prof. R. T. Leiper and Dr E. L. Taylor for their advice and help on technical points, and to Mr R. A. O. Shonekan, African laboratory assistant, for his able co-operation.

scholarly journals The rise and fall of diseases: reflections on the history of population health in Europe since ca. 1700

2021 ◽  
Author(s):  
Johan P. Mackenbach
Keyword(s):  
Public Health ◽  
Health Risks ◽  
The Body ◽  
Health Interventions ◽  
Epidemiological Transition ◽  
Public Health Interventions ◽  
Human Interventions ◽  
Ultimate Cause ◽  
History Of ◽  
Limited Usefulness

AbstractThis essay explores the amazing phenomenon that in Europe since ca. 1700 most diseases have shown a pattern of 'rise-and-fall'. It argues that the rise of so many diseases indicates that their ultimate cause is not to be sought within the body, but in the interaction between humans and their environment. In their tireless pursuit of a better life, Europeans have constantly engaged in new activities which exposed them to new health risks, at a pace that evolution could not keep up with. Fortunately, most diseases have also declined again, mainly as a result of human interventions, in the form of public health interventions or improvements in medical care. The virtually continuous succession of diseases starting to fall in the 18th, 19th and 20th centuries suggests that the concept of an “epidemiological transition” has limited usefulness.

Spatio-temporal variability of zoobenthic communities in a tectonic lagoon (Lake Vouliagmeni, Attika, Greece)

2008 ◽  
Vol 88 (5) ◽  
pp. 873-881 ◽  
Author(s):  
Chariton Chintiroglou ◽  
Chryssanthi Antoniadou ◽  
Panagiotis Damianidis
Keyword(s):  
Multivariate Analyses ◽  
Benthic Communities ◽  
Marine Species ◽  
Trophic Group ◽  
Spatial And Temporal Scales ◽  
Mediterranean Lagoons ◽  
Deposit Feeders ◽  
Spatio Temporal ◽  
Lagoon Lake ◽  
Hard Substrata

Lake Vouliagmeni (Attica, Greece) is a lagoon of great scientific interest due to its endemic fauna, widely used for recreational activities. Understanding the dynamics of this peculiar ecosystem is essential for its conservation. An ecological survey of the benthic communities was carried out, in both spatial and temporal scales. Material was collected with SCUBA diving, by taking off samples from the principal habitats of the lagoon, i.e. meadows, soft and hard substrata. The identification of the collected 61,975 living specimens revealed the presence of 12 floral and 20 faunal species. Multivariate analyses separated the sampling sites according to the four different habitats of the lagoon, whereas no temporal patterns came up. Micrograzers were the dominant trophic group, followed by deposit feeders regardless of the habitat studied. Lake Vouliagmeni is among the less diverse Mediterranean lagoons, mostly due to its isolation from the sea that hinders the entrance of marine species.

Constituency Agents and British Party Politics

1975 ◽  
Vol 5 (4) ◽  
pp. 459-476 ◽  
Author(s):  
Robert Frasure ◽  
Allan Kornberg
Keyword(s):  
Party Politics ◽  
Office Work ◽  
Job Descriptions ◽  
Large Numbers ◽  
History Of ◽  
And Training

We began by reviewing the history of agency and by describing the two major parties' procedures for recruiting and training agents. Not surprisingly, the perceptions that agents have of their roles is not entirely congruent with official perceptions. Approximately 20 per cent of the agents of both parties felt that the performance of various representational functions was the most important part of their job although these tasks are not included in official job descriptions. Moreover, although a majority of the agents in each party believed that their most important job was to build and maintain constituency organizations capable of winning elections, the majority of their time was not spent on this task. Conservative agents seemingly spent a disproportionate amount of time doing routine office work, whereas over 40 per cent of the Labour agents spent much of their time trying to raise the funds that paid their salaries. Large numbers of agents in both parties agreed that raising money in their constituencies was a difficult and largely unrewarding task.

“Only intelligent attendants need apply”: the history of Western Australia’s first asylum at Fremantle (1865–1909)

2021 ◽  
pp. 103985622110142
Author(s):  
Phil Maude
Keyword(s):  
Primary Sources ◽  
Work Roles ◽  
Large Numbers ◽  
Convict Transportation ◽  
History Of

Objective: To examine the history of Fremantle, Western Australia’s first purpose-built asylum. Method: A range of primary sources were consulted. Results: Fremantle was opened in 1865 to house inmates away from the populace and for the most part under the care of Dr HC Barnett. Attendants as well as inmates were occupied with work roles that kept the asylum functioning cost effectively. Conclusion: Within 15 years, the structure was neglected and overcrowded. Changes to the Penal Servitude Act limiting convict transportation, petty crime and a need to manage its proliferation resulted in large numbers of people being incarcerated at Fremantle.

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