How are velvet worms similar to arthropods?

Unlike arthropods, velvet worms do not have an exoskeleton, hence their limbs have no need for joints to facilitate mobility. On the head is a pair of sensory antennae, and small eyes. Velvet worms come in many colours among and even within species, possibly a camouflage function (Figure 1).

What did the velvet worm evolve from?

DNA evidence suggests velvet worms are closely related to crabs and spiders, possibly as a very early member of the group that gave rise to both. But fossil analysis seems to push the worm’s origins much farther back, relating it to a look-alike in 540-million-year-old rocks.

What is the common ancestor of all arthropods?

Described today in BMC Evolutionary Biology is a new species of lobopodian, a group that lived around 500 million years ago and is ancestral to modern arthropods – the animal group that includes insects, spiders, scorpions, and crustaceans.

Are velvet worms arthropods?

Velvet worms are generally considered close relatives of the Arthropoda and Tardigrada, with which they form the proposed taxon Panarthropoda. This makes them of palaeontological interest, as they can help reconstruct the ancestral arthropod.

Why are velvet worms closely related to arthropods?

Their name – Onychophora – means “claw-bearer”. Thought to be a missing link between Arthropods and Annelids, scientists now think that these ancient worms are more closely related to Arthropods. It’s these scales that give Onychophorans their velvety appearance. They also make their skin water repelling.

How did arthropods evolve?

It seems likely that arthropods evolved from the same root as the annelids and that the three main lineages of arthropods – the Chelicerata, the Crustacea and the Insecta – evolved independently from a common ancestor. Little is known of the ancestors of living arthropods.

When was velvet worm discovered?

Velvet worms are survivors. They belong to a clade that has been around for over 500 million years. Fossilized marine versions of velvet worms from the Cambrian period have been found in the Burgess Shale in Canada (505 million years old) and the Chengjiang formation in China (520 million years old).

How is a velvet worm important to the history of animal evolution?

Velvet worms are thought to be a well-preserved descendant of a prototypical animal from which arthropods (including insects, spiders, and crustaceans) were derived, as they share many important body-plan characteristics.

What do arthropods and segmented worms have in common?

Both arthropods and annelids are segmented, and members of the annelid class Polychaeta have a pair of appendages on each segment. The plan of the nervous system in arthropods is very similar to that of annelids, and the basic plan in both groups shows a tubular, dorsal heart, which is then lost or modified in some.

What did arthropods develop during these ancient times?

It appears the arthropods first evolved segmented limbs and then began to develop a hard exoskeleton. In basal arthropods, the head was limited to those segments which bore the eyes and short, stout antennae.

When did arthropods originate?

500 million years ago
Arthropods originated well over 500 million years ago. The trilobites, shown in this fossil from the Devonian Period (about 419 to 358 mya), were some of the earliest arthropods. The external skeleton, segmented body, and jointed appendages are clearly visible and were important evolutionary steps.