Search results
Results from the WOW.Com Content Network
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.
Starfish sometimes have negative effects on ecosystems. Outbreaks of crown-of-thorns starfish have caused damage to coral reefs in Northeast Australia and French Polynesia. [59] [70] A study in Polynesia found that coral cover declined drastically with the arrival of migratory starfish in 2006, dropping from 50% to under 5% in three years.
The Asterozoa are a subphylum in the phylum Echinodermata, within the Eleutherozoa.Characteristics include a star-shaped body and radially divergent axes of symmetry. The subphylum includes the classes Asteroidea (the starfish or sea stars), Ophiuroidea (the brittle stars and basket stars), Somasteroidea (early asterozoans from which the other classes most likely evolved), and Stenuroidea ...
For decades, scientists theorized a starfish didn’t have heads. A new study finds that they might, in fact, only have heads.
The crown-of-thorns starfish (frequently abbreviated to COTS), [1] Acanthaster planci, is a large starfish that preys upon hard, or stony, coral polyps (Scleractinia). The crown-of-thorns starfish receives its name from venomous thornlike spines that cover its upper surface, resembling the biblical crown of thorns. It is one of the largest ...
The most common corals in the subclass Hexacorallia have a hexameric body plan; their polyps have six-fold internal symmetry and a number of tentacles that is a multiple of six. Octamerism is found in corals of the subclass Octocorallia. These have polyps with eight tentacles and octameric radial symmetry.
The unusual animals have unique body plans arranged in five equal sections that differ greatly from the symmetric head-to-tail bodies of bilateral animals, which have left and right sides ...
The starfish can begin the metamorphosis into an adult once its characteristic radial symmetry is developed. Right after metamorphosis, the critter has a diameter of about 0.85 mm. Initial growth of the starfish is slow until the addition of the 6th arm, but once that happens, the addition of new arms occurs more rapidly.