Older brachiolaria larva of Asterias sp. from below, anterior end at top From Ernst Haeckel's Kunstformen der Natur (1904)
A brachiolaria is the second stage of larval development in many starfishes. It follows the bipinnaria. Brachiolaria have bilateral symmetry, unlike the adult starfish, which have a pentaradial symmetry. Starfish of the order Paxillosida (Astropecten and Asterina) have no brachiolaria stage, with the bipinnaria developing directly into an adult.
The brachiolaria develops from the bipinnaria larva when the latter grows three short arms at the underside of its anterior end. These arms each bear sticky cells at the tip, and they surround an adhesive sucker. The larva soon sinks to the bottom, attaching itself to the substrate, firstly with the tips of the arms, and then with the sucker. Once attached, it begins to metamorphose into the adult form.
The adult starfish develops only from the hind-part of the larva, away from the sucker. It is from this part that the arms of the adult grow, with the larval arms eventually degenerating and disappearing. The digestive system of the larva also degenerates, and is almost entirely rebuilt. A new mouth forming on the left side of the body, which eventually becomes the lower, or oral, surface of the adult. Similarly, a new anus forms on the right side, which becomes the upper, or aboral, surface.
The coelom, or body cavity is divided into three chambers in the larva, two of which form the water vascular system, while the other remains as the adult body cavity. Once the tube feet develop from the water vascular system, the larva frees itself from the bottom. At around the same time, the skeleton begins to develop, initially in a ring around the anus; at this point the larva has developed into an adult, although it will continue to grow for some years before reaching sexual maturity.
A brachiolaria is the second stage of larval development in many starfishes. It follows the bipinnaria. Brachiolaria have bilateral symmetry, unlike the...
the larval development of most starfish, and is usually followed by a brachiolaria stage. Movement and feeding is accomplished by the bands of cilia. Starfish...
their tips. Both bipinnaria and brachiolaria larvae are bilaterally symmetrical. When fully developed, the brachiolaria settles on the seabed and attaches...
It is during this time that the larvae, now brachiolaria, enters the benthic phase of life. The brachiolaria will settle exclusively on the red algae Mesophyllum...
members of this genus, the larva of Astropecten latespinosus is not a brachiolaria larva but is barrel-shaped and undergoes metamorphosis at a very early...
begin to feed they are called bipinnaria, this stage then grows into the brachiolaria after growing five arms, three fused with the central disk. The development...
developing embryo feeds on its egg yolk and hatches directly into a brachiolaria larva, without the intervening mobile planktonic phase of most starfish...
starfish has a 'bipinnaria' larva, which develops into a multi-armed 'brachiolaria' larva. A sea cucumber's larva is an 'auricularia' while a crinoid's...
becomes a gastrula in 2 to 3 days, a bipinnaria in 5 days, and finally a brachiolaria. Towards the end of the last stage the larva develops a large sack like...
to stages of all extant echinoderms, such as the bipinnaria and the brachiolaria of the starfish, the auricularia of the sea cucumbers, the echinopluteus...
anus and have no suckers on their tube feet. They do not develop the brachiolaria stage in their early development. They possess marginal plates, and have...
depth, but some at up to 1,000 m (3,300 ft). Porania pulvillus produces brachiolaria larvae in spring. It is gonochoristic. It feeds on detritus and the soft...
are used for swimming. They feed and grow but do not pass through a brachiolaria stage as do most starfish larvae. After about eighteen days they settle...
annulatus, but the larvae pass through at least one bipinnaria and one brachiolaria stage as has been demonstrated by DNA analysis. The larvae are planktonic...
planci and developed through the typical larval stages of bipinnaria and brachiolaria. Numbers of late-stage larvae were 10-29% of the original numbers of...
yolky eggs, which are fertilised externally, and the development of brachiolaria larvae. At first these rise to the surface but as they further develop...
immediately sink to the seabed. These soon start to develop into modified brachiolaria larvae, which have larval arms and attach with a sucker. By day seven...
(upper) surface or on the oral (under) surface of the animal. Two types of brachiolaria larvae appear to exist; some develop from yolky eggs and are non-swimming...
yolks and are retained inside the starfish which is viviparous. The brachiolaria larvae that develop inside the gonads "swim" in the fluid there and are...
starfish. The eggs are large and yolky and development is by way of brachiolaria larvae. In some species these are planktonic, but in others, the females...
fertilized eggs develop into planktonic larvae. Most species only produce brachiolaria larvae which are lecithotropic, non-feeding larvae. However, some Echinaster...
underwent the first stages of their development. Later they emerged and the brachiolaria larvae were brooded underneath the arched disc of the starfish. The breeding...
the seabed during this time but become pelagic for up to 6 months as brachiolaria larvae which allows them to disperse widely. They then return to the...
Global Information