|
How does it look like?
Aglaophenia pluma is a feather-shaped colonial hydrozoan. Its polyps, which in this class of cnidarians are called hydropolyps, have an envelope known as a hydrotheca in which they can be removed. The entire colony is enveloped by a chitinous covering that serves as a skeleton, which is called perisarc. Within the colony there are specialized individuals. Most of them are gastrozoa, which are responsible for capturing food for the whole group. There are also the so-called dactylozoa, which protect the gastrozoa by means of utricating cells, the cnidocytes. Finally, reproduction is carried out by the gonophores or gonothecae, which are found inside the corbulae. The feathers of Aglaophenia differ greatly in size, but can reach up to 15 centimeters in length.
Where does it live?
It is basically located throughout the Mediterranean and the north-east Atlantic. It is a benthic organism, therefore we will always find it fixed to the bottom, preferably in areas exposed to the current.
How does it feed?
It uses its sticky tentacles, the gastrozooids, to capture zooplankton or organic remains that circulate in the water.
How does it reproduce?
The reproduction of these organisms is quite complex, given that it can be sexual or asexual. To explain the type of reproduction we will base ourselves on a model species of the same genus well studied by experts, the Hydra that lives in fresh water.
-Asexual: The polypoid form always reproduces asexually, whether or not there is a jellyfish form. It is very common in colonial organisms, although some solitary genera such as Hydra can form buds that later detach from the parental organism. Asexual reproduction usually occurs by budding. Jellyfish also form from buds (gonopores) on polyps, either from the walls of common hydranths or on specialized gonozoa. In both cases the jellyfish have gonads and either can detach and swim freely, or remain on the polyps as reduced jellyfish.
-Sexual: All hydrozoans have a sexual phase in their life cycle. They are almost always dioecious. In groups that form jellyfish, these arise by budding from gonopores or gonozoa. The germ cells derive from interstitial epidermal cells that migrate to specific locations forming the gonads, which may be located on the manubrium or on the surface of the subumbrella (under the radial canals). Fertilization is usually external, although some species only release spermatozoa and fertilization of the egg occurs on the body of the female jellyfish. In those groups lacking the medusoid form, the polyps form simple and transient ectodermal gonads called sporosacs, which will be responsible for expelling the gametes. Fertilization will also generally be external.
Is a confusion possible?
It be confused with Eudendrium racemosum or Tubularia sp. One way to distinguish them is the difference in size. The genus Aglaophenia is clearly larger. If the size does not help us, we will have to rely on the characteristic feather-like morphology of Aglaophenia pluma.
Curiosities
· It does not possess toxins which can be harmful to humans.
· In the Mediterranean Sea the family Aglaopheniidae includes 14 species, very difficult to classify.
· On the feathers of Aglaophenia we can usually find the ghost shrimp, Caprella, or numerous species of nudibranchs of the family Dotidae, such as Doto koenneckeri. Often also the clutches of this group of slugs.
Taxonomy
Phylum: Cnidaria; Class: Hydrozoa; Subclass: Hydroidolina, Order: Leptothecata; Family: Aglaopheniidae; Genus: Aglaophenia |
