Question

A new marine animal species has been discovered. Locomotion is via a muscular foot. Digestive, nervous, excretory, reproductive, and respiratory systems are located in a visceral hump. The visceral hump displays torsion. The species has a coiled shell, and a head with tentacles and eyes. What phylum and class of the superphylum Lophotrochozoa should this species be classified in?

Answer 1

Answer:

Mollusca Phylum

Gastropoda class

Explanation:

The Mollusca Phylum is one of the most noticeable phyla that includes a wide variety of forms.

The ancestral Mollusca used to habit the pre-cambric oceans. It was bilaterally symmetrical, with a well-defined head that had tentacles and ocellus. Its ventral surface was plane and muscular, shaping a reptant foot. The dorsal surface was protected with a convex and oval shell.

The Gastropoda class is the richest class among all mollusks. This class experienced a characteristic torsion in their shell. This twist also involved the visceral mass, the mantle, and the mantle cavity. But by the time that this torsion occurred, the shell had already experienced a turn into a coil shape, which was then followed by its torsion.

The typical gasteropod´s shell is a conical structure composed of several tubular spirals containing the individual´s visceral mass. The biggest spiral ends as an opening from which the head and the food protrude.

Answer 2

Answer:

Phylum: Mollusca

Class: Gastropoda

Explanation:

The superphylum Lophotrochoza consist of animals with lophophore or trochophore larvae. It consist of five different phyla including phylum Platyhelminthes, Rotiferas, Nemertea, Mollusca and Annelida.

Out of all the five phyla, the molluscs are the only group that are predominantly marine with muscular foot, a visceral mass that houses the internal organs and a mantle that sometimes secrete calcareous shells.

There are 7 known classes in the phylum mollusca. These are;

• Aplacophora
• Monoplacophora
• Polyplacophora
• Bivalvia
• Gastropoda
• Cephalopoda
• Scaphopoda

These classes are often distinguished based on the presence or absence of shells and the type of shell if present. The only class with coiled (planospiral or conispiral) shell whose locomotion is via a ventral foot is Gastropoda.

Hence, taking the characteristics of the animal species discovered into cognizance, it should be classified in the phylum Mollusca and Class Gastropoda.