What is the function of nuchal organ?
The nuchal organ is a groove-like structure present near the posterior (backside) end of the prostomium of annelids. The main functions of this organ include the detection of light and food. It is also utilized for mating. Hence, they are known as epidermal sensory organs.
What do you mean by nuchal lobe?
The support cells of the olfactory region extend posteriorly. to form the nuchal lobes, or glands. The cells are elongate and taper to a thin neck just before. leaving the sensory area of the nuchal organ. There are essentially no nuclei in the sensory.
What is nuchal organ in nereis?
The nuchal organ is a ciliated pit or groove present at the posterior end of the prostomium of annelid worms, some cephalopods, and other invertebrates.
How do freshwater Polychaetes protect their larvae from osmotic stress?
The nereidid, Simplisetia limnetica, a freshwater polychaete found in the upper freshwater reaches of the Hawkesbury River, Sydney, Australia, may protect its developing young from osmotic stress by brooding them in its sedimentary galleries, which are more saline than overlying waters [26].
What do you call external bristles for movement in annelids?
Most annelids possess short external bristles called setae, or chaetae, composed of chitin. Setae are used to grip the soil, to hold the animal in a tube, or to increase the surface areas of appendages for swimming.
Where is the nuchal line located?
occipital bone
The nuchal lines are four curved lines on the external surface of the occipital bone: The upper, often faintly marked, is named the highest nuchal line, but is sometimes referred to as the Mempin line or linea suprema, and it attaches to the epicranial aponeurosis.
What does nuchal mean in pregnancy?
Nuchal (pronounced “NEW-kuhl”) translucency (NT) is an ultrasound that measures the amount of fluid behind your baby’s neck in the first trimester of pregnancy. A small amount of fluid is normal, and measuring the amount of fluid can help calculate your baby’s chances of having a chromosomal or genetic variant.
How are annelids important to humans?
In addition to improving soil fertility, annelids serve humans as food and as bait. Scientists observe annelids to monitor the quality of marine and fresh water.
Are marine worms osmoconformers?
Polychaete worms are widespread and diverse in marine and estuarine habitats subject to varying salinity, in areas influenced by tides, demanding physiological adjustment for internal homeostasis. They are typically considered and reported to be osmoconformers, but they are not often studied for their osmoregulation.
What are the excretory organs of annelids called?
Nephridia are the tubular excretory structures of earthworms and other annelids. Nephridia help to remove nitrogenous wastes and maintain a fluid and ionic balance.
What is the difference between setae and parapodia?
Setae, also known as parapodia or suckers, are paired structures present in Annelida for ease of locomotion. The annelids are bilaterally symmetrical, coelomates, triploblastic, and are invertebrates.
What are the four nuchal lines?
The nuchal lines are four curved lines on the external surface of the occipital bone: The upper, often faintly marked, is named the highest nuchal line, and to it the galea aponeurotica is attached.
…
Nuchal lines.
| Bone: Nuchal lines | |
|---|---|
| Gray’s | subject #31 130 |
How many nuchal lines are there?
The nuchal lines are four curved lines on the external surface of the occipital bone: The upper, often faintly marked, is named the highest nuchal line, but is sometimes referred to as the Mempin line or linea suprema, and it attaches to the epicranial aponeurosis.
What happens at a nuchal scan?
It involves a blood test and measuring the fluid at the back of the baby’s neck (nuchal translucency) with an ultrasound scan. This is sometimes called a nuchal translucency scan. The nuchal translucency measurement can be taken during the dating scan.
What causes extra fluid behind neck in fetus?
In the fetus fluid collects behind the neck, much like it does in dependent ankle oedema in later life. This occurs partly because of the fetus’s tendency to lie on its back and partly because of the laxity of the skin of the neck.
What are 5 examples of annelids?
Some common names for more well-known annelids include earthworms, sandworms, ragworms, bristle worms, and leeches. Annelid classes include Oligochaeta, Hirudinea, Polychaeta, and Archiannelida. Common characteristics in annelids include the body wall, metamerism, the cuticle, and the coelom.
What are annelids purpose?
Burrowing annelids, like the earthworm, play an important role in helping organic matter decompose. Earthworms eat dead plants and animals. When they eat, they also take in soil and tiny pebbles. Earthworms take in nutrients from microorganisms in the material they ingest.
Are freshwater fish hypotonic or hypertonic?
Although the skin of fish is more or less waterproof, the gills are very porous. The body fluids of fish that live in fresh water have a higher concentration of dissolved substances than the water in which they swim. In other words the body fluids of fresh water fish are hypertonic to the water (see chapter 3).
Is freshwater hypotonic or hypertonic?
hypotonic
Freshwater is hypotonic to Elodea A hypotonic solution is a solution that contains less (hypo) solutes than the cytoplasm of the cell. Thus, a hypotonic solution has more water than the cell and water has a tendency to move (diffuse) into the cell.
What is the name of excretory organ of cockroach?
Malpighian tubules
Malpighian tubules constitute the excretory organs of cockroaches and other insects.
What is the main excretory organ of earthworm?
Earthworms (annelids) have slightly more evolved excretory structures called nephridia, illustrated in Figure 22.10b. A pair of nephridia is present on each segment of the earthworm. They are similar to flame cells in that they have a tubule with cilia. Excretion occurs through a pore called the nephridiopore.
What is worm movement called?
The basic features of locomotion in annelids are most easily observed in the earthworm because it lacks appendages and parapodia. Movement involves extending the body, anchoring it to a surface with setae, and contracting body muscles.
Do leeches have hair?
Aquatic Segmented Worms and Leeches
They have 40–200 segments, all but the first of which contain four bundles of short to long hairs, or chaeta (in comparison to the abundant hairs found in polychaetes) in most species.
Do humans have a nuchal ligament?
Here’s the nuchal ligament, also called the ligamentum nuchae. It’s a sheet of strong fibrous tissue that extends from the spinous process of the first thoracic vertebra, to the external occipital protuberance. The nuchal ligament limits forward flexion of the head and the cervical spine.
What are the 3 scans in pregnancy?
Different Types of Pregnancy Ultrasound Scans Explained
- The Dating Scan.
- Screening for Down’s, Edwards’ and Patau’s Syndromes.
- The Gender Scan.
- The Mid-Pregnancy Scan.
- Third-Trimester Scans.
- Standard 2D Scans.
- 3D Scans.
- 4D Scans.