What evidence is used to link annelids, arthropods and molluscs evolutionarily?

Question

please explain...

I also want to know what evidence is used to separate annelids, arthropods and molluscs from the echinoderms and chordates

Answer 1

you can't seperate them.. they are their own groups of animals yet all intertwined..

annelids are rather basic animals.. a-coelemates, coimplete digestive tract, simple circulation..

if you were to lay them out they form almost a line of evolutionary progressive steps.. it is in this way that they are related

http://universe-review.ca/I10-82-familyt...

as you can see.. each group has characteristic of the previous groups.. an one or more evolutionary 'advances' (i really don't like that word) such as non-symmetric sponges, then radially symmetric cnidarians.. then bilatterally symmetric worms and so on..

Answer 2

Annelids, arthropods and mollusks are all protostomes.  Echinoderms and chordates are deuterostomes.

When  the digestive tract is forming, first one hole opens up, then it forms a tube and then opens up on the other side.

In protostomes, the first hole becomes the mouth, the second hole becomes the a**s.  In deuterostomes, the first hole becomes the a**s, the second becomes the mouth.

Answer 3

Annelids

The annelids, collectively called Annelida (from Latin anellus "little ring"), are a large phylum of animals comprising the segmented worms, with about 15,000 modern species including the well-known earthworms and leeches. They are found in most wet environments, and include many terrestrial, freshwater, and especially marine species (such as the polychaetes), as well as some which are parasitic or mutualistic. They range in length from under a millimeter to over 3 meters

Arthropods

Arthropods are animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, "joint", and ποδός podos"foot", which together mean "jointed feet") and include the insects, arachnids, crustaceans and others. Arthropods are characterized by the possession of a segmented body with appendages on at least one segment. They have a dorsal heart and a ventral nervous system. All arthropods are covered by a hard exoskeleton made of chitin, a polysaccharide, which provides physical protection and resistance to desiccation. Arthropods grow by shedding this covering in what are termed molts.

molluscs

Molluscs (British spelling) or mollusks (American spelling) are animals belonging to phylum Mollusca. The word mollusc is derived from the French mollusque, which originated from the Latin molluscus, meaning thin-shelled, from mollis, soft[2]. The scientific study of molluscs is known as malacology.

There are around 100,000 extant species within the phylum with an estimated 70,000 extinct species. They range widely in size from micromolluskan snails and clams to larger organisms such as the Colossal Squid, believed to be the world's largest invertebrate. Molluscs are typically divided into ten taxonomic classes, of which two are entirely extinct. Class Cephalopoda molluscs such as squid, cuttlefish and octopus are among the most neurologically-advanced of all invertebrates

Evolution.

During the time of evolution There was many different types of organisims lots!

The name Articulata is applied to the Clitellata, Euarthropoda, Onychophora, Pogonophora, Polychaeta, and Vestimentifera. The Vestimentifera is the sister group to, or more likely a clade within, the frenulate pogonophores, and the name Pogonophora is retained for this group. In half of the 18 minimal length trees, the traditionally formulated Annelida, i.e. Polychaeta and Clitellata, is paraphyletic if the Pogonophora are excluded. In the remaining minimal length trees, a monophyletic Annelida cannot be formulated. The name Annelida should not be used unless relationships within the Articulata are resolved to show it is a monophyletic taxon.

The taxon name Articulata, originally formulated to include the Annelida and Arthropoda by Cuvier, is defined as the clade stemming from the first ancestor to show repetition of homologous body structures derived by teloblastic growth with a pygidial growth zone (segmentation) and longitudinal muscles broken into bands. The Articulata is considered, on current evidence, to consist of four monophyletic groups; the Arthropoda, Clitellata, Polychaeta, and Pogonophora, though the latter group may be a clade of polychaetes. If this is shown, the Pogonophora should revert to the original family name Lamellisabellidae Uschakov, 1933. An indented classification reflective of the cladistic pattern is provided. Other recent hypotheses about metazoan systematics are analysed.

I think this was because of Phylogenetic relationships of annelids, molluscs, and arthropods evidenced from molecules and morphology. Journal of Molecular evolution  

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