Calycophorae is a suborder of Siphonophorae alongside two other suborders Physonectae and Cystonectae.
Distribution
Calycophorae are found generally in every deep sea
Pelagic zone environments.
The location and depth of distribution depends on the species of Calycophorae.
The species Muggiaea bargmannae belongs to the family
Diphyidae which have been found at depths between 400 and 2000 meters at both poles at a latitude between 36~87°N and 43~71°S.
The species Hippopodius hippopus of the family
Hippopodiidae on the other hand, have been observed to live at a depth between 0 and 300 meters at the latitudes 50°N~38°S.
Morphology
All
Siphonophorae including Calycophorae are composed of
, which each have a function within the organism including but not limited to feeding,
reproduction, and locomotion.
The body plan of a Calycophorae can be divided into its
nectophore and its
siphosome.
A typical Calycophorae has two nectophores that have ostia that are either facing the opposite or same directions.
For aligned nectophores, the nectophores are classified as anterior and posterior with the latter being the one behind.
Within the nectophore are the
somatocyst and the
hydroecium.
The somatocyst is an additional structure that is seen in the
mesoglea of Calycophorans where oil globules are stored as a food source and also serve to provide
buoyancy.
The
hydroecium is a ventral cavity that exists in the posterior nectophore.
The siphosome is the stem of the Calycophoran on which the bracts,
, and
are attached to with the bracts serving as a protective cover.
The bracts also contain a
phyllocyst that also contains oil globules.
Each group of these zooids is called a
cormidium and repeats itself throughout the siphosome.
Each gastrozooid has an elongated
tentacle that has several side tentacles called tentilla that have pads or batteries of
nematocysts which are connected to the tentacle by a pedicel.
There are some exceptions to this common morphology such as the
Hippopodiidae that have several overlapping nectophores and
Sphaeronectidae that have one nectophore.
Locomotion
The
contract to push water out of the
ostium and propels the
organism forward.
In some Calycophorans, the
siphosome can be retracted into the
hydroecium to reduce drag.
Some Calycophorans have replaced up to 75% of heavy sulfate ions in their bracts with lighter chloride ions to increase their
buoyancy to compensate for their lack of
pneumatophores.
Feeding
All
Siphonophorae are predatory
including the Calycophorans.
The
on the
Tentacle inject
into prey that come in contact with the nematocysts.
The toxins paralyze the prey immobilizing it, which is then brought to the
gastrozooid for
digestion and redistribution of nutrients.
The prey of Calycophorans depend on the species but are commonly small
such as
, gelatinous
zooplankton, or even small fish.
Reproduction
The Calycophorae are
monoecious and have three stages in their life cycle which are the larval development stage, the polygastric stage (maturity stage), and the
eudoxid stage (sexual
reproduction stage).
The bracts which contain
and
on a Calycophorae detach from the
siphosome once maturity is reached.
This detached bract becomes a free living eudoxid that releases male or female
depending on its determined
sex.
A successfully fertilized gamete enters the larval development stage in which asexual reproduction takes over to recreate a full polygastric colony.
Taxonomy
From molecular phylogenetics it has been confirmed that Calycophorae evolved from the
Physonectae.
175
species of
Siphonophorae have been identified of which 5 are of
Cystonectae (which includes the Portuguese man o' war) and the rest are of
Codonophores.
There are 16 families under Codonophora and 7 families under Calycophorae:
Prayidae,
Hippopodiidae,
Clausophyidae,
Sphaeronectidae,
Diphyidae,
Abylidae, and
Tottonophyidae.
Other relevant information
Current debates
The differences in the structure and function of
are often studied to determine the different species of
Siphonophorae, and the loss or addition of zooids usually signify
speciation.
Current debates contemplate whether or not the Siphonophores including Calycophorans as a whole are losing or gaining zooid types.
Specimen collection
Siphonophorae in general are fragile and using nets would shred the
organism into pieces.
For descriptive analysis, specimens need to be carefully collected by research submersibles into capsules which takes much more time and effort.
These complications are a setback to the study of Calycophorans.
However, some locations such as the bay at Villefranche-Sur-Mer, have special abiotic conditions that push up Siphonophores to the shore.
These specimens are readily collectible and have contributed to much of our knowledge of Siphonophores.
