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#phylum

13 public questions tagged with this topic.

Regeneration -ll

Sea urchins belong to which phylum?

Sea urchins display classic echinoderm traits that place them firmly within phylum Echinodermata alongside starfish, brittle stars, and sea cucumbers. Adults show pentaradial symmetry, endoskeletal ossicles with spines, and a water vascular system operating tube feet for locomotion and feeding. Embryologically they are deuterostomes with radial cleavage, enterocoelic coelom formation, and blastopore becoming anus, aligning them phylogenetically closer to chordates than molluscs or arthropods. Bilateral larvae metamorphose into radial adults, confirming echinoderm affiliation rather than chordate, molluscan, or arthropod body plans.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 1: Echinoderm embryology and phylogenetic position within Deuterostomia.

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Sea urchin -l

Sea urchins belong to which phylum?

Sea urchins are familiar marine invertebrates characterized by pentaradial symmetry as adults, water vascular system with hydraulic tube feet, endoskeleton composed of interlocking calcareous ossicles bearing spines, and classic deuterostome development where blastopore becomes anus and coelom forms enterocoelically. These anatomical and embryological traits uniquely define Phylum Echinodermata, class Echinoidea, alongside starfish, brittle stars and sea cucumbers. Their phylogenetic proximity to chordates makes them powerful model for gene regulatory network evolution. Mollusca, Arthropoda and Chordata lack this combination of radial adult symmetry, ambulacral system and mesodermal calcified skeleton, confirming echinoderm affinity.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 8: Echinoderm phylogeny - sea urchins in Phylum Echinodermata.

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Dictyostelium

Dictyostelium discoideum belongs to the phylum:

Dictyostelium discoideum belongs to Amoebozoa, a major eukaryotic supergroup defined by lobose pseudopodia, tubular mitochondrial cristae, and lack of flagellated vegetative forms. Historically misplaced in fungi due to fruiting body shape, molecular phylogenomics places it among cellular slime molds distant from fungi and plants. This explains phagocytic feeding on bacteria, actin-driven motility, and chemotactic aggregation. Amoebozoan context underscores why it serves as evolutionary model illuminating transition between unicellular protist lifestyle and regulated multicellular development, signaling, and altruistic differentiation with kin selection.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 22: Dictyostelium - aggregation, cAMP relay and multicellular morphogenesis.

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