What is the type of fertilization in Nereis?

Fertilization can be external (outside body) or internal (inside body). For e.g. in Nereis, fertilization is external in sea water.

What are the morphological features of Nereis?

Nereis worms are commonly known as rag worms or clam worms. The body is long, slender, and dorso-ventrally flattened, reaching a length of 5-30 cm. The head consists of two parts: a roughly triangular anterior lobe—the prostomium—and a posterior ring-like portion—the peristomium.

What is the larva of Nereis?

The name of the larva of Nereis is trochophore.

What is Nereis Palp?

(2) Palp—paired, elongated and compact and located after the tentalces. (3) Eyes—two pairs, simple, round, pigmented and present on the dorsal side of the head. The peristomium carries: (1) Peristomial tentacles—four pairs, long, slender, cylindrical and laterally placed.

Why is Nereis called sand worm?

Alitta virens (common names include sandworm and king ragworm; older scientific names including Nereis virens are still frequently used) is an annelid worm that burrows in wet sand and mud. It was first described by biologist Michael Sars in 1835. It is classified as a polychaete in the family Nereididae.

Why Nereis is called clam worm?

Nereis is a typical polychaete genus, living in burrows in sand or mud, often with clams, a reason for which its species are commonly known as clamworms or sandworms.

How do Nereis respire?

Respiratory System of Nereis Gills are absent in Nereis . The function of respiration is taken over by the lobes of parapodia and dorsal integument. For this reason, these regions are richly supplied with blood vessels.

What is Notopodium and Neuropodium in Nereis?

The dorsal ramus is the notopodium (noto = back, pod = foot) and the ventral ramus is the neuropodium (neuro alludes to the nerve cord, which is ventral). Each ramus bears clusters of chitinous bristles, or chaetae.

Is Nereis parasitic?

Parasitic. Hint: Nereis or Neanthes Fucata is the simplest segmented marine polychaete ringworm. They have around 200 segments or metameres. The initial segment of its body has been fused to form its head consisting of the eyes and peristomium (part of the head in Phylum Annelida).

How do clam worms reproduce?

Clam worms do not have permanent gonads. Instead, during the reproductive season, special cells release sperm and beautiful aqua eggs into the body cavity. At this same time the worm transforms into a reproductive form called an epitoke.

What is respiratory pigment in nereis?

The blood of the annelids usually contains hemoglobin, a red oxygen carrying pigment. In some annelids, erythrocruorin is present. It is a large oxygen-carrying protein.

Does nereis have closed circulatory system?

These considerations lead to the further conclusion that the vascular lumen in Nereis is essentially interstitial space and that the system, which has been known as a typical “closed” circulatory system in annelids, is actually an open circulatory system.