Which one of the following is not correctly matched ?

Question

Accepted Answer

The correct option is 4: Rhabditiform - larva Wuchereria banchrofti

This question requires a thorough understanding of the life cycles and characteristic larval forms across various invertebrate phyla, a key area in comparative biology. The correct answer is Option 4 because it presents a biologically *incorrect* match, which is what the question is asking for. The parasitic nematode, *Wuchereria bancrofti*, is the causative agent of lymphatic filariasis (elephantiasis), and its life cycle involves specific larval stages: the minute, sheath-covered **microfilaria** (L1) found in the blood of the human host, and the **filariform larva** (L3) which is the infective stage transmitted by the mosquito vector. Crucially, the **Rhabditiform** larval stage is *not* a developmental stage in the life cycle of *Wuchereria bancrofti*. The term 'Rhabditiform' is typically used to describe the first larval stage of soil-transmitted nematodes, such as hookworms (*Ancylostoma*) and *Ascaris*, or the free-living generation of *Strongyloides*, which are characterized by a muscular esophagus with a distinct bulb. Since *Wuchereria* directly produces microfilariae that develop within an arthropod vector, the pairing of Rhabditiform with this organism is inaccurate.

The incorrect option is 1: Ephyra - Larva Aurelia

This pair is correctly matched, making it an incorrect answer to the question. *Aurelia* (the moon jellyfish) belongs to the Class Scyphozoa (Phylum Cnidaria), and its life cycle includes a characteristic alternation of generations. In this cycle, the sessile polyp stage, known as the scyphistoma, undergoes a process called strobilisation, which results in the detachment of a small, disc-shaped, free-swimming larva. This larval form, which eventually grows into the adult medusa, is correctly named the **Ephyra**.

The incorrect option is 2: Parenchymula - larva Porifera

This association is factually correct, making it a viable biological pair but the wrong selection for this question. The Phylum Porifera (sponges) reproduces sexually, producing various ciliated larval forms for dispersal. The **Parenchymula** is one of the two main types of larval stages found in sponges, particularly in the Class Demospongiae. It is a solid, non-hollow larva where the ciliated cells cover the entire outer surface, allowing it to swim and seek a suitable substrate before settling down to begin its sedentary adult life.

The incorrect option is 3: Cydippid - larva Ctenophora

This match is also biologically accurate and, therefore, an incorrect choice for the question asking for the wrongly matched pair. The Phylum Ctenophora, commonly known as comb jellies, are characterized by their eight rows of ciliary plates (comb rows). Their developmental process is usually direct, with the larva often resembling a miniature adult ctenophore. This larval form is universally referred to as the **Cydippid larva**, a name derived from the adult Cydippida order. The Cydippid larva possesses the features of the adult, including the comb rows and a pair of tentacles, confirming that the match is correct.