Spontaneous hatching of Fallacohospes inchoatus, an umagillid flatworm from the northeastern Pacific crinoid Florometra serratissima

1986 ◽  
Vol 64 (9) ◽  
pp. 2068-2071 ◽  
Author(s):  
George L. Shinn
Keyword(s):  
Suspension Feeding ◽  
Free Swimming ◽  
Mode Of Reproduction ◽  
Egg Capsules ◽  
Complete Development ◽  
The Family ◽  
Northeastern Pacific ◽  
Deposit Feeding

Egg capsules of Fallacophospes inchoatus are roughly tetrahedral in shape, have a hydratable adhesive covering, and typically contain two zygotes and 40–50 yolk cells. Embryos complete development in 40–42 days and hatch spontaneously when kept in seawater at 8–10 ° C. This observation suggests that the suspension-feeding crinoid hosts are infected by eating free-swimming larvae rather than by eating egg capsules that contain embryos, which is the case for deposit-feeding echinoderms that harbour umagillids. The possibility is raised that umagillids originally evolved as parasites of suspension-feeding echinoderms and that the mode of reproduction of crinoid-inhabiting umagillids is primitive for the family.

Two new species of stalked crinoids from the northeastern Pacific in the genera Gephyrocrinus and Ptilocrinus (Echinodermata, Crinoidea, Hyocrinidae). Effects of ontogeny and variability on hyocrinid taxonomy

Zootaxa ◽  
2011 ◽  
Vol 2825 (1) ◽  
pp. 1 ◽  
Author(s):  
MICHEL ROUX ◽  
PHILIP LAMBERT
Keyword(s):  
British Columbia ◽  
New Species ◽  
Single Species ◽  
Depth Range ◽  
Evolutionary Trend ◽  
Exceptional Collection ◽  
The Family ◽  
Two New Species ◽  
Northeastern Pacific ◽  
Stalked Crinoids

Two new species of deep-sea stalked crinoids belonging to the family Hyocrinidae were collected in the northeastern Pacific. The descriptions contain detailed information on character variations and ontogeny. The five specimens of Gephyrocrinus messingi n. sp. lived at depths ranging from 1,777 m to 2,110 m off British Columbia and California. This new species is the first record of the genus Gephyrocrinus in the Pacific Ocean, which was previously known from only a single species, G. grimaldii, from the northeastern Atlantic at the same depth range. The two species illustrate opposing phenotypes within the same genus. Fifty-eight specimens of the second new species, Ptilocrinus clarki n. sp., were dredged off British Columbia close to the type-locality of P. pinnatus, the type species of the genus Ptilocrinus, but at shallower depths ranging from 1,178 to 1,986 m. This exceptional collection provides significant data on intraspecific variation in the main morphological characters, especially arm pattern. The ontogeny of stalk articulations and the main traits of adoral plate differentiation are described in detail. A complementary investigation on P. pinnatus was conducted using specimens collected by the “Albatross” expedition at a depth of 2,906 m. Despite similarities in external morphology, tegmen and cover plates, the two ptilocrinid species display significant differences in pinnule architecture, aboral cup and stalk articulations. From comparison with Gephyrocrinus messingi n. sp. and Ptilocrinus clarki n. sp., G. grimaldii and P. pinnatus are interpreted as the result of heterochronic development by paedomorphy after ecological or geographic isolation. Pinnule architecture in the two new species suggests first steps in an evolutionary trend toward a rigid box which protects gonad inflation in the proximal part of the pinnule. These new data on Ptilocrinus and Gephyrocrinus create problems in the current taxonomy of the family Hyocrinidae. The main derived characters, especially in pinnule and arm pattern, are used to propose new hypotheses for hyocrinid phylogeny.

Ultrastructure of the podia of Amphiura chiajei and Amphiura filiformis and their role in feeding

2006 ◽  
Vol 86 (4) ◽  
pp. 817-822 ◽  
Author(s):  
John K. Keogh ◽  
Brendan F. Keegan
Keyword(s):  
Chemical Composition ◽  
Morphological Study ◽  
Secretory Cells ◽  
Suspension Feeding ◽  
Head Region ◽  
Feeding Styles ◽  
Amphiura Filiformis ◽  
The Difference ◽  
Mucus Cells ◽  
Deposit Feeding

Morphological study of the podia of the suspension feeding Amphiura filiformis and the deposit feeding Amphiura chiajei revealed sensory–secretory complexes in the podial epidermis, consisting of four cells, two secretory and two sensory. Large mucus cells were found in association, but not exclusively, with the sensory–secretory complexes. In A. filiformis, mucus cells stained positively for both acid and neutral mucopolysaccharides, while, in A. chiajei, these cells stained only for acid mucopolysaccharides. The surfaces of the arm podia in A. chiajei were relatively smooth, while the arm podia of A. filiformis bear papillae. The sensory–secretory complexes open through numerous paired pores, with each pair having an intervening cilium. Pores were restricted to the podial tip in A. chiajei, while in A. filiformis they are concentrated on the podial tip and on the papillae. Amphiura chiajei shows very little differentiation of the podia along the length of the arm. In A. filiformis, the distal podia have papillae throughout their entire length, with pores being found on the head region and the papillar tips. Here, the papillae are oriented in such a way (i.e. facing inward towards the ventral arm plate) as to increase the area of the filtering surface of the podium, serviced by the sticky secretions from the sensory–secretory complexes. The proximal podia are relatively simple in structure and are thought to function more in the transportation of mucus wrapped particles to the mouth rather than in their capture. The difference in structure of the podia and chemical composition of podial secretory cells are taken to reflect the difference in feeding styles of the two species.

Newly discovered parasitic Turbellaria of opisthobranch gastropods

2010 ◽  
Vol 91 (5) ◽  
pp. 1123-1133 ◽  
Author(s):  
Kosuke Sudo ◽  
Yoshiaki J. Hirano ◽  
Yayoi M. Hirano
Keyword(s):  
Life History ◽  
Obligate Parasite ◽  
Egg Capsules ◽  
Parasitic Worm ◽  
The Family

An endoparasitic platyhelminth from six species of sacoglossan opisthobranchs was collected at several localities of temperate to subtropical waters in Japan. Poecilostomatoid copepods (all species of Splanchnotrophidae and several species of Philoblennidae) and a few digenean flukes had been the only endoparasitic metazoans known for opisthobranch hosts. The newly discovered parasite was 1 to 15 mm in length and had no eyes, mouth, pharynx, or intestine. It had no external organs for parasitic life (e.g. attachment organs) and inhabited the haemocoel of the host. When mature, it emerged from the host and secreted a silky substance around itself to form a cocoon. The cocoon contained egg capsules with 19–42 eggs. Larvae, hatched from the capsule, had a ciliated body and a pair of eye spots. They were negatively phototactic and capable of invading suitable hosts. These morphological and life history features suggest this parasitic worm may belong to the family Fecampiidae (Platyhelminthes: Turbellaria), one of a few obligate parasite taxa in Turbellaria. Molluscan hosts which are common for parasitic Platyhelminthes have not previously been known for this family. The newly discovered parasite may be important for understanding the evolution of parasitism in Platyhelminthes.

scholarly journals Rays and Skates (Raiœ) No. 1.—Egg-Capsules and Young

1922 ◽  
Vol 12 (4) ◽  
pp. 578-643 ◽  
Author(s):  
Robert S. Clark
Keyword(s):  
Egg Capsules ◽  
The Family ◽  
Northern Distribution

The family Raiidæ belongs to the division Batoidei of the sub-order Hypotremata, and is represented by the principal genera Raia, Psammobatis, and Sympterygia (Regan, 1906). The genus Raia (an altered spelling of Raja) was instituted by Linnæus, after Artedi, for the type Raja batis in the Systema Naturæ, Ed. X, Vol. I, 1758. The species are numerous and mostly of northern distribution.

Observations on the tubicolous annelidMagelona alleni(Magelonidae), with discussions on the relationship between morphology and behaviour of European magelonids

2018 ◽  
Vol 99 (4) ◽  
pp. 715-727 ◽  
Author(s):  
Kimberley Mills ◽  
Kate Mortimer
Keyword(s):  
Environmental Parameters ◽  
Current Paper ◽  
Suspension Feeding ◽  
Surface Deposit ◽  
Laboratory Environment ◽  
Feeding Modes ◽  
The Family ◽  
Multiple Feeding ◽  
The Relationship

AbstractFeeding, defecation, palp behaviour and motility of the tubicolous annelid,Magelona alleniwere observed in a laboratory environment. Both surface deposit, and to a lesser extent, suspension feeding were exhibited, with the ingestion of sand grains, and of smaller amounts of foraminiferans and administered commercially available suspension. Predominantly sand could be seen moving through the gut, resulting in conspicuous defecation, not previously observed in other magelonid species. During this ‘sand expulsion’ behaviour, individuals turned around in a network of branched burrows. The posterior was extended from the burrow and substantial amounts of sand were expelled in a string-like formation, involving mucus. The posterior morphology ofM. allenidiffers greatly compared with other European magelonid species, in possessing a large terminal anus, likely related to its diet. In contrast to what has been recorded for other magelonids,M. alleniappears predominately non-selective. The current paper adds credence to the idea that multiple feeding modes exist within the family. Tube-lined burrows were observed to be primarily permanent, and motility of the species reduced in comparison to other magelonids. The differences noted betweenM. alleniand other species is most likely linked to its tubicolous lifestyle. The effect of environmental parameters on observed behaviours is discussed.

Cercarial emergence of Proterometra macrostoma and P. edneyi (Digenea: Azygiidae): contrasting responses to light: dark cycling

Parasitology ◽  
1989 ◽  
Vol 99 (2) ◽  
pp. 215-223 ◽  
Author(s):  
M. C. Lewis ◽  
I. G. Welsford ◽  
G. L. Uglem
Keyword(s):  
Field Experiments ◽  
Life Cycles ◽  
Snail Host ◽  
Differential Sensitivity ◽  
Free Swimming ◽  
Complete Development ◽  
Emergence Patterns ◽  
Fish Hosts ◽  
Cercarial Emergence ◽  
Constant Dark

SummaryProterometra macrostoma and P. edneyi infect the same snail host, Goniobasis semicarinata, but different fish hosts in their life-cycles. Cercariae of P. macrostoma complete development in sunfish, those of P. edneyi in darters; fish become infected when they ingest free-swimming cercariae as ‘prey’. Laboratory and field experiments were designed to test the hypothesis that light: dark (L: D) cycling regulates emergence of both species. Under L: D cycling conditions, P. macrostoma emerged in the dark and P. edneyi in the light. These emergence patterns resulted from differential sensitivity to light and dark. In the laboratory and field, reversing the light and dark periods resulted in corresponding alterations in emergence patterns of both species. Both species emerged in constant light and constant dark, but their emergence patterns were altered. Emergence patterns may represent adaptations that make the cercariae more susceptible to ‘predation’ by their respective fish hosts.

New species of holothurian (Echinodermata: Holothuroidea) from hydrothermal vent habitats

2000 ◽  
Vol 80 (2) ◽  
pp. 321-328 ◽  
Author(s):  
A.V. Smirnov ◽  
A.V. Gebruk ◽  
S.V. Galkin ◽  
T. Shank
Keyword(s):  
New Species ◽  
Hydrothermal Vent ◽  
Hydrothermal Vents ◽  
East Pacific Rise ◽  
The West ◽  
West Pacific ◽  
East Pacific ◽  
The Family ◽  
Hydrothermal Environment ◽  
Deposit Feeding

A new holothurian species Chiridota hydrothermica (Apodida: Chiridotidae) is described, restricted to hydrothermal vent habitats. The new species is known from the west Pacific (Manus and North Fiji Basins) and the South East Pacific Rise, between 17 and 21°S. The unusual large, lobe-like tentacles of this holothurian, uncommon in the family Chiridotidae, could be an adaptation to facilitate shifts between suspension- and deposit-feeding in the hydrothermal environment. A brief review of all known records of holothurians and other echinoderms at hydrothermal vents is given.

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