Question

select all the correct answers.

which two of these characteristics are examples of endoskeletons?

• scales in fish
• bones in mammals
• calcium-rich plates in echinoderms
• appendages in arthropods

Explanation:

Define endoskeletons

An endoskeleton is an internal support structure of an animal, composed of mineralized tissue (like bone or cartilage) or calcium-rich plates, located deep within the soft tissues. This contrasts with an exoskeleton, which is a hard outer protective covering.

Analyze scales in fish

Fish scales are part of the integumentary system (the outer protective layer of the skin). They are dermal structures located on the exterior surface of the body rather than acting as an internal structural framework, so they are not considered part of the endoskeleton.

Analyze bones in mammals

Using the Mammal Characteristics and Vertebrate Comparison knowledge points, we know that mammals are vertebrates. Vertebrates possess an internal bony framework. The bones in mammals provide structural support, protect internal organs, and facilitate movement from within the body, making them a classic example of an endoskeleton.

Analyze calcium-rich plates in echinoderms

Echinoderms (such as sea stars and sea urchins) possess an internal skeleton composed of calcium carbonate plates called ossicles. These plates are located beneath the outer epidermal layer of skin, which makes them a true internal skeletal system, or endoskeleton.

Analyze appendages in arthropods

Arthropods (such as insects, spiders, and crustaceans) are characterized by having a hard outer cuticle made of chitin that forms an exoskeleton. Their jointed appendages are supported and moved by muscles attached to the inner surface of this external shell, not an internal skeleton.

Answer:

• scales in fish
• bones in mammals (Correct answer)
• calcium-rich plates in echinoderms (Correct answer)
• appendages in arthropods