Anguillicoloides novaezelandiae facts for kids

Anguillicoloides novaezelandiae is a tiny worm that lives inside eels. It's a type of parasite, which means it lives off another animal, called a host. This worm makes its home in the swimbladders of eels, especially certain types like the Anguilla australiensis, Anguilla anguilla, and the Anguilla dieffenbachii.

This worm is found in places like New Zealand, where it naturally lives. It has also been found in Italy, where scientists think it was brought by accident.

About This Worm

Anguillicoloides novaezelandiae is very similar to another worm called A. australiensis. However, there are some key differences that help scientists tell them apart.

How It Looks Different

The head of A. australiensis is shaped like a big, round bulb, with a clear narrow part right after it. But the head of A. novaezelandiae is only slightly wider, not as round.

Also, in female A. australiensis worms, a part called the anterior ovary reaches almost halfway down their oesophagus (food tube). In A. novaezelandiae females, this part doesn't reach the end of the oesophagus.

Size Differences

These two types of worms also have different sizes and shapes. A. australiensis is long and thin. Males can be about 30 to 40 millimeters (1.2 to 1.6 inches) long. Females carrying eggs (called gravid females) can be 60 to 70 millimeters (2.4 to 2.8 inches) long and up to 1.5 millimeters (0.06 inches) wide.

In contrast, A. novaezelandiae is much shorter and wider. Males are usually between 6 and 15 millimeters (0.2 to 0.6 inches) long. Gravid females are between 10 and 31 millimeters (0.4 to 1.2 inches) long and can be up to 3 millimeters (0.12 inches) wide. The back end of the female body also looks different in these two species.

What is Anguillicolosis?

When an eel has these Anguillicola worms living inside it, this condition is called anguillicolosis. It's like saying the eel has a worm infection.

Worm Features

This worm is medium-sized for a nematode and has a dark color. Its outer skin, called the Epicuticle, is smooth and doesn't have any spines.

Head and Body

The head of the worm has a slight narrow part, like a neck, just before its nerve ring. The mouth part, called the buccal capsule, is small and hard. It has tiny teeth around the mouth.

The worm's oesophagus, or food tube, gets wider in its back half. The part of the oesophagus that helps push food through is well-developed. The nerve ring is located below the neck area.

Internal Parts

The excretory pore, which is where waste leaves the body, is near where the oesophagus joins the intestine. The intestine itself is dark, mostly straight, and wide.

The worm has three large, oval-shaped glands called rectal glands. Sometimes, a smaller one might also be present. The tail of the worm is shaped like a cone and comes to a point.

Worm Length

Male worms are typically between 5.5 and 8.57 millimeters (0.22 and 0.34 inches) long. Female worms are usually between 7.17 and 13.63 millimeters (0.28 and 0.54 inches) long.