A lamprey, a shark, a lizard, and a rabbit share all the following characteristics except
a. Pharyngeal slits in the embryo or adult.
b. Vertebrae.
c. Hinged jaws.
d. A dorsal, hollow nerve cord.

Verified step by step guidance

1. Identify the key characteristics shared by all the organisms listed: lamprey, shark, lizard, and rabbit. These organisms are all chordates, so they share certain fundamental traits such as pharyngeal slits, a dorsal hollow nerve cord, a notochord, and a post-anal tail at some stage of their development.
2. Analyze the characteristic 'pharyngeal slits in the embryo or adult.' All chordates, including the lamprey, shark, lizard, and rabbit, possess pharyngeal slits during their embryonic development, even if they are not retained in the adult form.
3. Examine the characteristic 'vertebrae.' All the organisms listed, except the lamprey, have true vertebrae. Lampreys are jawless vertebrates, but their vertebrae are rudimentary and not fully developed like those in sharks, lizards, and rabbits.
4. Evaluate the characteristic 'hinged jaws.' Lampreys lack hinged jaws, as they are jawless vertebrates (agnathans). Sharks, lizards, and rabbits, however, all possess hinged jaws, making this a distinguishing feature.
5. Consider the characteristic 'a dorsal, hollow nerve cord.' This is a defining feature of all chordates, including the lamprey, shark, lizard, and rabbit, and is present in all these organisms during their development.

Key Concepts

Pharyngeal Slits

Pharyngeal slits are openings in the pharynx that occur in the embryonic development of all chordates. In some species, these structures develop into gills, while in others, they may contribute to the formation of various structures in the head and neck. Understanding their presence in different organisms helps in identifying evolutionary relationships among species.

Vertebrae

Vertebrae are the individual bones that make up the vertebral column, or spine, in vertebrates. This structure provides support and protection for the spinal cord, and its presence is a defining characteristic of the subphylum Vertebrata. Recognizing which organisms possess vertebrae is crucial for classifying them within the animal kingdom.

Hinged Jaws

Hinged jaws are a significant evolutionary adaptation that allows for more efficient feeding mechanisms in vertebrates. They enable organisms to grasp, manipulate, and process food more effectively than species without jaws. This feature is particularly important in distinguishing between different groups of vertebrates, such as jawed and jawless fish.