Which organism has the least specialized organization?

Question

Which organism has the least specialized organization??  
A. Earthworm  
B. Starfish  
C. Spider  
D. Sponge

Accepted Answer

Correct Answer: (D)Sponge. 
Rationale: The sponge has the least specialized level of biological organization among the options.Biological organization progresses from simple to complex: chemical, cellular, tissue, organ, organ system, organism. Sponges (phylum Porifera) are at the cellular level of organization. Their bodies are loose aggregates of several distinct cell types (e.g., choanocytes for feeding, amoebocytes for transport) that perform specific functions, but these cells are not organized into true tissues. There is minimal coordination between cells, no nervous system, and no organs. In contrast, the other options are all animals with true tissues and organs, representing more complex organizational levels.A) EarthwormEarthworms are annelids with a high degree of organization. They possess true organs arranged into complex organ systems: a closed circulatory system with hearts, a digestive system with specialized regions, a nervous system with a simple brain and ventral nerve cord, and excretory organs (nephridia). They exhibit organ-system level organization.B) StarfishStarfish are echinoderms with complex internal organization. They have a true coelom and well-developed organ systems, including a unique water vascular system for locomotion, a digestive system, and a nervous system. Their larval stages are bilaterally symmetric, and adults exhibit pentaradial symmetry, but they are far more complex than sponges.C) SpiderSpiders are arthropods, among the most complex invertebrates. They have specialized organ systems: a sophisticated nervous system, respiratory structures (book lungs and/or tracheae), a digestive system, excretory Malpighian tubules, and complex reproductive organs. They represent a very high level of specialization.D) SpongeSponges are the simplest multicellular animals. They lack true tissues and organs. Their body is a sac-like structure with pores. Cells work somewhat independently, and the animal's form is maintained by a simple skeleton of spicules or protein fibers. This represents the most primitive and least specialized body plan in the animal kingdom.ConclusionWhen ranking animals by organizational complexity, sponges are foundational. They represent the transition from unicellular life to multicellularity but have not evolved the tissue-level integration seen in all other animals. Earthworms, starfish, and spiders all possess true tissues and organs, placing them at more advanced organizational levels.

Which organism has the least specialized organization?

A
Earthworm

B
Starfish

C
Spider

D
Sponge

The sponge has the least specialized level of biological organization among the options.

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Related Questions

Which organism has the least specialized organization?

A Earthworm B Starfish C Spider D Sponge

The sponge has the least specialized level of biological organization among the options.

Topic Flashcards

Mini Quiz

Related Questions

A
Earthworm

B
Starfish

C
Spider

D
Sponge