Animals belonging to the phylum Chordata are characterized by having a notochord, a hollow dorsal nerve cord, and pharyngeal slits at some point during their development. These features are crucial for defining vertebrates, a subphylum of Chordata that includes animals possessing a vertebral column or backbone. Among the given options, jellyfish are not vertebrates, while the remaining animals, including lizards, horses, grasshoppers, and birds, are vertebrates. Let’s delve into each of these animals in detail to understand their vertebrate characteristics.
Jellyfish, scientifically known as cnidarians, are invertebrates. They lack a vertebral column and do not possess any semblance of a backbone. Instead, they have a gelatinous body with a simple structure that consists of a bell-shaped body and tentacles for capturing prey. Their body is predominantly composed of water and lacks any skeletal structure.
Lizards are reptiles, which are a diverse group of vertebrates. They belong to the class Reptilia, characterized by their scaly skin and ectothermic nature. Lizards possess a well-developed vertebral column, which provides support and protection to their internal organs. This backbone is composed of a series of individual vertebrae, which are connected by ligaments and allow for flexibility and movement.
Horses are large, herbivorous mammals belonging to the family Equidae. Mammals are a class of vertebrates known for their ability to nurse their young with milk and possess specialized teeth. Horses, like all mammals, have a well-developed vertebral column. This backbone is composed of a series of vertebrae, which not only provide support and protection but also serve as attachment points for muscles, tendons, and ligaments.
Grasshoppers belong to the class Insecta, which is the largest class within the phylum Arthropoda. Arthropods are invertebrates, but unlike jellyfish, they possess an exoskeleton, which is a hard external covering that provides support and protection. However, grasshoppers are not vertebrates as they lack a true vertebral column. Instead, they have a segmented body supported by an internal structure called the exoskeleton.
Birds are warm-blooded vertebrates belonging to the class Aves. They are characterized by their feathers, beaks, and the ability to lay hard-shelled eggs. Birds possess a highly modified vertebral column, which provides support for their body and allows for flight. The vertebral column of birds is specialized to be lightweight and has fused vertebrae in certain regions, providing rigidity and strength necessary for aerial locomotion.
In conclusion, among the given options, lizards, horses, and birds are vertebrates, while jellyfish and grasshoppers are not. It is essential to understand the distinguishing characteristics of vertebrates, such as possessing a vertebral column or backbone, in order to classify and differentiate animals accurately.