Quiz #2: Lower Invertebrates

The statement is true because the human liver fluke, Clonorchis sinensis, is indeed common in China and can cause cirrhosis of the liver and death. This parasite infects the liver and bile ducts of humans, leading to inflammation, scarring, and eventually liver damage. If left untreated, it can result in severe complications such as liver cancer and even death. Therefore, the statement is accurate.

Polychaetes and Mollusca both have a trochophore larvae during their first larval stage. This is a characteristic that they share, indicating a common evolutionary history. The trochophore larvae is a distinct larval form characterized by a ring of cilia around the body, which is important for locomotion and feeding. This stage is present in both Polychaetes and Mollusca, supporting the statement that they share this characteristic. Therefore, the answer is true.

Ocelli are light-sensitive sense organs found in flatworms. They are simple eyes that can detect changes in light intensity and direction. These organs help flatworms to navigate their environment and respond to light stimuli. Ocelli are not as complex as the eyes of higher organisms, but they still play a crucial role in the sensory perception of flatworms.

Only members of Class Cephalopoda (e.g squid, octopus) in mollusk have a closed circulatory system.

Protonephridia (first kidney) is a specialized organ in flatworms osmoregulation and it also helps eliminating other matabolic wastes such as ammonia, urea and amino acid.

Ctenophores are marine animals that possess eight comb rows composed of long, fused cilia. Cilia are hair-like structures that extend from the surface of cells and are involved in various functions such as locomotion and capturing food. In the case of ctenophores, the fused cilia in their comb rows help them move through the water by beating in a coordinated manner, creating a shimmering effect. This allows them to swim and navigate their environment efficiently.

Most of members in Phylum Nematoda are dioecious with amoeboid sperm, and males are smaller than females and have a bent tail for holding female for copulation.

The cuticle in nematodes serves several functions, including acting as a barrier and providing protection, functioning as a sensory array to detect changes in the environment, and serving as a hydrostatic skeleton to aid in locomotion. However, it does not act as a hook to burrow into muscle tissue forming cysts for parasitic nematodes.

Earthworms are hermaphroditic, meaning they possess both male and female reproductive organs. However, they are not self-fertilizing, which means they cannot fertilize their own eggs with their own sperm. Instead, earthworms engage in cross-fertilization, where they exchange sperm with another earthworm during mating. This allows for genetic diversity and prevents inbreeding.

It is believed that all coelomate animals may evolved from flatworm-like ancestors.

Of all mollusks, only the bivalves lack a radula.

Members in the Phylum Nematoda possess a pair of lateral sensory organs called amphids. Amphids are specialized structures found in nematodes that are responsible for detecting chemical cues in the environment. They play a crucial role in the nematode's ability to sense and respond to their surroundings.

Both of subclasses Hirudinea (e.g leeches) Oligochaeta are placed under Class Clitellata (having a clitellum).

Each colloblast cell consists of bulbous, sticky head connected to a long, straight filament and a spiral, contractile filament.

The body of ctenophores has ctene which is organized into 8 comb rows. These comb rows = costae stretch from oral to aboral surface and the function is for locomotion.