Are Chaetognatha deuterostomes?

Are Chaetognatha deuterostomes?

Indeed, chaetognaths display some embryological characters considered typical of deuterostomes (a gut with a mouth not arising from blastopore and a mesoderm derived from the archenteron by enterocoely), whereas their morphology recalls the organization of the protostomes (ventral nerve cord and chitinous structures) ( …

Are arrow worms deuterostomes?

Arrow worms (the phylum Chaetognatha), which are among the major marine planktonic animals, are direct developers and exhibit features characteristic of both deuterostomes and protostomes. In particular, the embryonic development of arrow worms appears to be of the deuterostome type.

What does the name Chaetognatha mean?

The Chaetognatha /kiːˈtɒɡnəθə/ or chaetognaths /ˈkiːtɒɡnæθs/ (meaning bristle-jaws) are a phylum of predatory marine worms that are a major component of plankton worldwide.

Is Chaetognatha a Holoplankton?

They are hermaphrodites, each bearing large paired ovaries and testes. Development is direct. All are strongly carnivorous feeding primarily on copepods. Known to undertake diel vertical migration to track the vertical movements of their prey.

Why is the phylogenetic placement of chaetognaths uncertain?

Problems arise because of the lack of morphological and physiological diversity within the group. In addition, no unambiguous chaetognaths are preserved as fossils, so nothing about this groups evolutionary origins can be learned from the fossil record.

What do arrow worms feed on?

Arrow worms eat plankton, including tiny crustaceans, fish larvae, and other arrow worms.

Are Chaetognatha chordates?

As the likely sister group of chordates, hemichordates are indeed half (or part) chordates. Two chordate subphyla—Urochordata and Cephalochordata— are also invertebrate groups. Phylum Chaetognatha traditionally has been included among deuterostomes, but this arrangement is not supported by recent molecular evidence.

How do chaetognaths reproduce?

Reproduction in chaetognaths is unique. All chaetognaths are hermaphroditic, meaning they have both male and female parts. Eggs are formed in the trunk region of the body, whereas the sperm develop in the tail portion. Sperm can sometimes be seen swimming inside the tail portion of the body.

Are crabs Holoplankton?

Meroplankton spend only the larval or early stages of their life as part of the plankton and spend their adult lives on the reef. Meroplankton includes sea urchins, starfish, sea squirts, most of the sea snails and slugs, crabs, lobsters, octopus, marine worms and most reef fishes.

Do worms eat algae?

Worms eat almost everything in the soil — fungi, invertebrate life, leaves, twigs, algae, moss and microscopic life.

Where do we find most marine worms in the ocean?

Marine worms are found throughout the world’s oceans from salt marshes to coral reefs to deep sea hydrothermal vents. They can be found burrowed into the mud or sand, under rocks, in algae, free swimming, or attached to their host. Some species are colonial, so you can find hundreds in one place.