Rhopalia (singular rhopalium) are the most obvious sensory structures of scyphozoan jellyfish. They include specialized structures for
sensing light (eyespots) and movement or direction with respect to gravity
(statoliths).
How many rhopalia are found on a jellyfish?
In each of the
four rhopalia
located at the corners of the jellyfish’s cube-shaped body there are two lens eyes 2 and four pigment-pit eyes (two upper pit eyes and two lower slit eyes).
How many Rhopalia are visible in Aurelia?
The sense complices of Aurelia are the
eight rhopalia
evenly spaced around the margin of the bell (Fig 2, 7-48). Each rhopalium contains a statocyst for gravity detection, mechanoreceptors, chemoreceptors, and an ocellus for photoreception.
Where are the rhopalia located?
Rhopalia are club-shaped bodies located
around the bell margin in medusae of scyphozoans and cubozoans
, with the number typically in multiples of four (Fig. 1c–g; Hyman 1940).
What is meant by rhopalium?
Rhopalia (singular: rhopalium) are
small sensory structures of Scyphozoa (typical jellyfish)
and Cubozoa (box jellies). … Specialized structures to sense light (ocelli) and perceive gravity (statoliths) are usually present. They also control the pace of swimming-muscle contraction.
Are rhopalia eyes?
Cubozoans have the most intricate visual apparatus within Cnidaria. It comprises four identical sensory structures, the rhopalia, each of which
holds six eyes of four morphological types
. Two of these eyes are camera-type eyes that are, in many ways, similar to the vertebrate eye.
What is mesoglea made of?
ectoderm of coelenterates is the mesoglea, a gelatinous mass that
contains connective fibres of collagen and usually some cells
. Both layers contain muscle fibres and a two-dimensional web of nerve cells at the base; the endoderm surrounds a central cavity, which ranges from simple to complex in shape and serves…
Which is seen in Aurelia?
| Aurelia aurita | Aurelia aurita, Red Sea | Scientific classification | Kingdom: Animalia | Phylum: Cnidaria |
|---|
What is the anatomy of a jellyfish?
They are composed of three layers:
an outer layer, called the epidermis
; a middle layer made of a thick, elastic, jelly-like substance called mesoglea; and an inner layer, called the gastrodermis. An elementary nervous system, or nerve net, allows jellyfish to smell, detect light, and respond to other stimuli.
What is the function of Cnidocytes?
Cnidocytes (‘stinging cells’) are specialized cells that define the phylum Cnidaria (sea anemones, jellyfish, corals and hydras). They contain an “explosive” organelle called cnidocyst that acts as a 600 million-years-old microscopic injection system and is
important for prey capture and anti-predator defense
.
What is the meaning of nematocysts?
: one of the
stinging capsular organelles
of the tentacle of a cnidarian (such as a box jellyfish or sea anemone) that contains a coiled, hollow, usually barbed, venomous thread which is discharged especially for catching prey and defending against enemies Each nematocyst contains a spiral-coiled thread tipped with a …
What are nematocysts biology?
Nematocyst, minute,
elongated, or spherical capsule produced exclusively by members of the phylum Cnidaria
(e.g., jellyfish, corals, sea anemones). … After eversion, the thread separates from the nematocyst. The threads of some nematocysts ensnare small prey by wrapping about them.
Is mesoglea is present in annelida?
The answer to the above question is option D :
Arthropoda
.
Is mesoglea edible?
Both the gel-like mass – the mesoglea – and the layers called epithelium are indigestible for humans in their natural form. … This leads in the end to a crunchy texture of the jellyfish and
transforms the actually inedible mesoglea into edible material
.
Do Coelenterates have mesoderm?
Since coelenterates
possess only body cavity and no development of mesoderm
in germ layer and no true internal coelom, they are not considered coelomates in which well differentiated organs can be accommodated.
What is the life cycle of Aurelia?
The canonical life cycle of Aurelia sequentially includes
a fertilized egg, planula, scyphistoma, strobila, ephyra and medusa
[28]. However, the planula may undergo vegetative multiplication or develop directly into an ephyra shortly after settling (Fig 5I), without the formation of a scyphistoma [54].
