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Earthworm head. Depending on the species, an adult earthworm can be from 10 mm (0.39 in) long and 1 mm (0.039 in) wide to 3 m (9.8 ft) long and over 25 mm (0.98 in) wide, but the typical Lumbricus terrestris grows to about 360 mm (14 in) long. [9]
The worm has a hydrostatic skeleton and moves by longitudinal and circular muscular contractions. Setae – tiny hair-like projections – provide leverage against the surrounding soil. Surface movements on moist, flat terrain were reported at a speed of 20 m/h and, based on measurements of the length of the trail, nocturnal activity away from ...
Earthworms store their partners' sperm in spermathecae ("sperm stores") and then the clitellum produces a cocoon that collects ova from the ovaries and then sperm from the spermathecae. Fertilization and development of earthworm eggs takes place in the cocoon. Leeches' eggs are fertilized in the ovaries, and then transferred to the cocoon.
Oligochaeta (/ ˌ ɒ l ɪ ɡ ə ˈ k iː t ə,-ɡ oʊ-/) [1] is a subclass of soft-bodied animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms.
The genus Lumbricus contains some of the most commonly seen earthworms in Europe among its nearly 700 valid species. [2] Characteristics of some commonly encountered species are: Lumbricus rubellus is usually reddish brown or reddish violet, iridescent dorsally, and pale yellow ventrally. They are usually about 25–105 mm in length, and have ...
YouTube videos: Planaria eating worm segment, Planarian; Schmidtea mediterranea, facts, anatomy, image at GeoChemBio.com; Alejandro Sanchez-Alvarado's Seminar: Regeneration in Planarians; Link to an article discussing some work on planarian immortality; A user-friendly visualization tool and database of planarian regeneration experiments
Nereis are osmoconformers.They are dioecious (individuals are male or female) and they release their haploid gametes into the water, a process called spawning.Moreover, upon fertilization and mitotic divisions of the zygote, Nereids form a larval stage which is similar to that of molluscs – i.e. a trochophore larva.
Alitta succinea (known as the pile worm, clam worm or cinder worm) [3] is a species of marine annelid in the family Nereididae (commonly known as ragworms or sandworms). [4] It has been recorded throughout the North West Atlantic, as well as in the Gulf of Maine and South Africa .