What are the species of Chaetognatha?
The Chaetognatha /kiːˈtɒɡnəθə/ or chaetognaths /ˈkiːtɒɡnæθs/ (meaning bristle-jaws) are a phylum of predatory marine worms that are a major component of plankton worldwide. Commonly known as arrow worms, about 20% of the known Chaetognatha species are benthic, and can attach to algae and rocks.
Who is known as arrow worms?
Chaetognaths, also known as ‘arrow worms’, have been important predators in the world’s oceans since the Cambrian. While only around 130 chaetognath species are known, they are nevertheless hugely abundant, showing the success of their life style.
Is chaetognaths Triploblastic?
Triploblastic relationships with emphasis on the acoelomates and the position of Gnathostomulida, Cycliophora, Plathelminthes, and Chaetognatha: a combined approach of 18S rDNA sequences and morphology.
What are the process of reproduction in Chaetognatha?
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 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.
What do arrow worms eat?
plankton
Arrow worms eat plankton, including tiny crustaceans, fish larvae, and other arrow worms.
Do arrow worms have a complete digestive tract?
This refers to the grasping spines near the mouth. The teeth have neurotoxins that help them kill their prey. They do not have circulatory or respiratory systems and have only a simple nervous system. They have a complete digestive tract and are coelomates.
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.
Do worms eat algae?
Worms eat almost everything in the soil — fungi, invertebrate life, leaves, twigs, algae, moss and microscopic life.
What do arrow worms look like?
PHYSICAL CHARACTERISTICS. Arrow worms are long, straight, narrow sea worms that use hooks for catching prey. Arrow worms that live near the surface are clear, which helps them avoid predators. The intestines of species that live in middle depths often are yellow or red because they eat prey of those colors.
What kind of body does a Chaetognatha have?
Chaetognaths range from 1 mm to 12 cm in length and are typically transparent, although some deep-water species may be orange in color (carotenoid pigmentation), and phragmophorids may be opaque, due to their musculature. They are bilaterally symmetrical and have long, streamlined bodies, which may be divided into head, trunk, and tail regions.
How big does a Chaetognatha arrow worm get?
Maximum adult body length: 105 mm; tail: 10-18 % of body length. Chaetognaths belong to an exclusively marine phylum commonly known as arrow worms. There are around 100 species in the phylum, of which 10 are known from south-east Australian waters.
How big does a Chaetognatha phragmophorid get?
Chaetognaths may range from 1 mm to 12 cm in length and are typically transparent, although some deep-water species may be orange in color, and phragmophorids may be opaque, due to their musculature.
What kind of algae do chaetognathas attach to?
Chaetognatha. About 20% of the known species are benthic, and can attach to algae and rocks. They are found in all marine waters, from surface tropical waters and shallow tide pools to the deep sea and polar regions. Most chaetognaths are transparent and are torpedo shaped, but some deep-sea species are orange.