Balanoglossus
| Balanoglossus | |
|---|---|
 |
|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Hemichordata |
| Class: | Enteropneusta |
| Order: | Enteropneusta |
| Family: | Ptychoderidae |
| Genus: |
Balanoglossus Delle Chiaje, 1829 |
| Species | |
|
See text. |
|
See text.
Balanoglossus is an ocean-dwelling acorn worm (Enteropneusta) genus of great zoological interest because, being a Hemichordate, it is an "evolutionary link" between invertebrates and vertebrates. Balanoglossus is a deuterostome, and resembles the Ascidians or sea squirts, in that it possesses branchial openings, or "gill slits".It has notochord in the upper part of the body and has no nerve chord. It does have a stomochord, however, which is gut chord within the collar. Their heads may be as small as 2.5 mm (1/10 in) or as large as 5 mm (1/5 in).
J.F. Eschscholtz who discovered Balanoglossus in 1825 in Mashail Island described it as a worm-like holothurian. The discovery of gill-slits in this animal by Kowalewsky (1865) led to creation of a special class Enteropneusta by Gegenbaur (1870). Bateson (1885) included them in Phylum Chordata. Hyman (1959), however, placed them near Echinodermata and gave Hemichordata a status of an independent phylum.
This simple organism shows affinities with several diverse groups.
Balanoglossus is a tuberculos or burrowing and exclusively marine animal. It is found in shallow waters between tide marks along the coast of warm and temperate oceans.
Balanoglossus clavigerus is a U-shaped excavated in a sandy bottom
Nemertines resemble flatworms and possess a long protrusible proboscis. Balanoglossus shows similarity with nemertine in burrowing and feeding habits. The proboscis of nemertines is compared with proboscis of Balanoglossus. These similarities are superficial as the proboscis of Balanoglossus.is not protrusible as in nemertines. The Balanoglossus. also does not have lateral nerve cord of nemertines.
These are worm-like tube-dwelling animals living in the bottom of shallow seas.
The paired sacs given off from the stomach of phoronids are compared with buccal diverticulum of Balanoglossus.
The nervous system in both the groups is intraepidermal.
The power of regeneration is seen in both the groups.
The actinotroch larva of Phoronis is similar to tornaria larva of Balanoglossus.
...
Wikipedia