Spionidae

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Spionidae
Scolelepis squamata

Scolelepis squamata

Systematics
Empire : Animals (Animalia)
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Subclass : Canalipalpata
Order : Spionida
Family : Spionidae
Scientific name
Spionidae
Pit , 1850

Spionidae is the name of a family of small to medium-sized polychaeta (polychaeta) living as filter feeders, more than 100 species of which are found in oceans worldwide.

features

The many-bristles of the family Spionidae often have a rounded and cut-off prostomium , but this can also be pointed or have a pair of lateral horns. It is noticeably elongated to the rear and bears a pair of bulbous (caruncle-like) nuchal organs . The animals have 2 to 6 eyes. A middle antenna can be present or absent. At the peristomium there are always two long and highly mobile palps with a longitudinal groove, which serve for nutrition. Except in the first segment, where notopodia may be missing in some species, the parapodia are forked with typical leaf-shaped notopodia and neuropodia . While dorsal and ventral cirrus are always absent, gills are often present, either only on the first few segments or on most of the segments. The gills sit on the back next to the lobes of the notopodia , with which they can be partially or completely fused. They are usually more or less flattened, can simply be ciliated on the sides or have feathers or lamellae. Two elongated anal cirrus or numerous smaller cirrus or lobes can sit on the pygidium. While aciculae and composite bristles are absent, the bristles on the notopodia and neuropodia are simple smooth or edged hair bristles or simple hooks with apical teeth, sometimes coated, or barbs or altered spines. In many Spionidae all segments are similar, but in Polydora and some related genera the 5th segment is modified and has various other types of bristles, including simple spines.

Distribution, habitat, way of life

The Spionidae are widespread in seas around the world and are found in a wide variety of marine, benthic habitats. Representatives of the genera Polydora and Boccardia in particular are able to drill into hard limestone and can therefore seriously damage mussel beds and coral sticks. Other species live in sedimentary soils or mud and can occur in large numbers. The sand-dwelling Spiophanes bombyx is cosmopolitan and the most common species in the eastern part of the German Bight with 28% of all multi- bristle individuals.

The Spionidae live mainly on the surface of sediment soils as filter feeders or substrate eaters , where she and her two palps ingest food particles and transport through the batting gutters to mouth.

Development cycle

The Spionidae can be divided into two groups with regard to the type of fertilization: In the genera Aonides , Laonice , Prionospio , Spiophanes , Scolelepis and Malacoceros , the gametes are released into the open sea water, where fertilization takes place. In Spio , Microspio , Polydora and the genera related to the latter, males and females copulate so that internal fertilization takes place; in many species in this group the larvae initially develop in egg capsules before they come to life as free-swimming larvae. The shape of the egg capsules and the larvae differs depending on the species; In addition to diet via yolks, there are also species with nutritional eggs in the capsules. Towards the end of the free-swimming phase, the larva sinks to the bottom and metamorphoses into a creeping worm. In the breeding species Streblospio benedicti there are two reproductive strategies with yolk -poor eggs and plankton-eating larvae on the one hand and yolk-rich eggs on the other.

Some species of the Spionidae are known to reproduce asexually by autotomy, including Pygospio elegans .

Systematics

Spio seticornis  (Figures 1-7) and Spio filicornis  (Figures 8-12). Otto Fabricius (1785): From the Spio sex, a new worm sex .

The first type was Spio seticornis 1767 by Carl Linnaeus as Nereis seticornis described, and in 1776 was followed by the description of the later as the type species specific Spio filicornis by Otto Friedrich Müller under the name Nereis filicornis . The Danish clergyman Otto Fabricius , author of the Fauna Groenlandica (not to be confused with his contemporary, the zoologist Johann Christian Fabricius ), recognized the peculiarities of these annelids and established the genus Spio with the two species Spio seticornis and Spio filicornis . In 1850 Adolph Eduard Grube described the Spiodea family as "Aricieen with 2 long antennae".

The Spionidae family includes around 38 genera with around 115 described species :

etymology

The name of the family is derived from the generic name Spio, which comes from Speio , a sea nymph ( Nereid ) in Greek mythology, analogous to the Nereiden family .

literature

Web links

Commons : Spionidae  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Klaus J. Götting, Ernst F. Kilian, Reinhard Schnetter: Introduction to Marine Biology 1: Marine Organisms - Marine Biogeography. Friedrich Vieweg and Son, Braunschweig / Wiesbaden 1982. p. 97.
  2. ^ Wilhelm Vollmer : Dictionary of the Mythology of All Nations: With 129 panels , Hoffmann'sche Verlagsbuchhandlung, Stuttgart, 1836. S. 1454. Retrieved on January 25, 2019.