Haleciidae
Encyclopedia
The Haleciidae are a hydrozoa
n family
of the suborder Conica
. Their hydroid
colonies emerge from a creeping hydrorhiza and usually form upright branching colonies; some species' colonies are stolon
al though. Their gonophores are typically sporosacs, growing singly or bunched into a glomulus. They remain attached to the hydroids or break off to be passively drifted away; in a few, the gonophores are naked.
Some enigmatic actively-swimming medusa
e have been tentatively placed in this family as a knid of "wastebin taxon
". Should their associated hydroids turn out to belong elsewhere, they are to be moved to that family and genus. The relationships of this fairly small but distinctive radiation
to other conican Leptomedusae
are not well understood at present; the Lovenellidae
, however, typically turn out to contain the hydroid stage of medusae placed in the Haleciidae.
diaphragm
, with a row of small knobs distally to it. They are so small in height as to lack an operculum
, but are maintained and repaired throughout the individual animal's life. The hydranth much exceed the hydrothecae in size and are quite sturdy. Their endoderm
consists of a proxmal digestive and a distal non-digestive section. The tentacles of some but not all carry webbing between them; likewise, the presence of nematophores, nematothecae and nematodactyls varies throughout this family.
of Haleciidae recognized in modern times, only as few as 4 might actually be valid genera of this family. The others are suspected of either only containing the medusa
e of some other family's hydroid
s, or to be synonymous with other Haleciidae genera, or are otherwise of doubtful validity.
Hydrozoa
Hydrozoa are a taxonomic class of very small, predatory animals which can be solitary or colonial and which mostly live in saltwater. A few genera within this class live in freshwater...
n family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of the suborder Conica
Conica (Hydrozoa)
Conica are a cnidarian suborder of the Leptomedusae . They make up the bulk of their order; their internal relationships are not well resolved, and most of the roughly 30 families are not yet assigned to a superfamily....
. Their hydroid
Hydroid
-Marine biology:Hydroids are a life stage for most animals of class Hydrozoa, small predators related to jellyfish.-Botany:In mosses, hydroids form the innermost layer of the stem of long, colourless, thin walled cells of small diameter.The cells are dead and lack protoplasm.They function as water...
colonies emerge from a creeping hydrorhiza and usually form upright branching colonies; some species' colonies are stolon
Stolon
In biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons.-In botany:...
al though. Their gonophores are typically sporosacs, growing singly or bunched into a glomulus. They remain attached to the hydroids or break off to be passively drifted away; in a few, the gonophores are naked.
Some enigmatic actively-swimming medusa
Medusa (biology)
In biology, a medusa is a form of cnidarian in which the body is shaped like an umbrella, in contrast with polyps. Medusae vary from bell-shaped to the shape of a thin disk, scarcely convex above and only slightly concave below...
e have been tentatively placed in this family as a knid of "wastebin taxon
Wastebin taxon
Wastebasket taxon is a term used in some taxonomic circles to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined by their lack of one or more distinct character states or by their not belonging to one or more other taxa...
". Should their associated hydroids turn out to belong elsewhere, they are to be moved to that family and genus. The relationships of this fairly small but distinctive radiation
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...
to other conican Leptomedusae
Leptomedusae
Leptomedusae or Leptomedusa, commonly called thecate hydroids, are a cnidarian order in the subclass Leptolinae. They were formerly placed at suborder rank in the paraphyletic "Hydroida"...
are not well understood at present; the Lovenellidae
Lovenellidae
The Lovenellidae are a hydrozoan family of the suborder Conica. Their hydroids live together in upright stolonal or sympodial colonies, and their gonophores are pedunculate free-roaming medusae....
, however, typically turn out to contain the hydroid stage of medusae placed in the Haleciidae.
Description
The shallow, usually even-rimmed hydrothecae are sessile or borne on a hydrophore; their bottom is formed by a concentricConcentric
Concentric objects share the same center, axis or origin with one inside the other. Circles, tubes, cylindrical shafts, disks, and spheres may be concentric to one another...
diaphragm
Diaphragm
-Optics and photography:* Diaphragm , a stop in the light path of a lens, having an aperture that regulates the amount of light that passes* Diaphragm shutter, a type of leaf shutter consisting of a number of thin blades in a camera-Acoustics:...
, with a row of small knobs distally to it. They are so small in height as to lack an operculum
Operculum
Operculum may refer to:*Operculum , a stiff structure resembling a lid or a small door that opens and closes**Operculum , a lid on the shell of some gastropods**Operculum , a lid on the orifice of some bryozoans...
, but are maintained and repaired throughout the individual animal's life. The hydranth much exceed the hydrothecae in size and are quite sturdy. Their endoderm
Endoderm
Endoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm and mesoderm , with the endoderm as the intermost layer...
consists of a proxmal digestive and a distal non-digestive section. The tentacles of some but not all carry webbing between them; likewise, the presence of nematophores, nematothecae and nematodactyls varies throughout this family.
Genera
Of the 10 generaGenera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
of Haleciidae recognized in modern times, only as few as 4 might actually be valid genera of this family. The others are suspected of either only containing the medusa
Medusa (biology)
In biology, a medusa is a form of cnidarian in which the body is shaped like an umbrella, in contrast with polyps. Medusae vary from bell-shaped to the shape of a thin disk, scarcely convex above and only slightly concave below...
e of some other family's hydroid
Hydroid
-Marine biology:Hydroids are a life stage for most animals of class Hydrozoa, small predators related to jellyfish.-Botany:In mosses, hydroids form the innermost layer of the stem of long, colourless, thin walled cells of small diameter.The cells are dead and lack protoplasm.They function as water...
s, or to be synonymous with other Haleciidae genera, or are otherwise of doubtful validity.
- Baleum
- Campalecium Torrey, 1902 (medusae of Lovenellidae?)
- Diplocyathus Allman, 1888
- HaleciumHaleciumHalecium is a genus of hydrozoa in the Haleciidae family, consisting of approximately 120 species. These marine invertebrates are found in all oceans, where they often form large colonies....
Oken, 1815 (= Thoa) - Hemitheca (nomen dubiumNomen dubiumIn zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
) - Hydranthea Hincks, 1868 (sometimes in Lovenellidae)
- Hydrodendron Hincks, 1874 (= Diplocathus)
- Nemalecium
- Ophiodissa Stechow, 1919 (might belong in Hydrodendron)
- Saaba