Diversity in Living Organisms

Olynthus belongs to class Calcarea.

Aracheocytes are amoeboid cells which exhibit the phenomenon of totipotency.

Freshwater sponges host green algae as endosymbionts within archaeocytes and other cells. 

The amniotic egg is the key evolutionary innovation that allowed reptiles (and later birds and mammals) to reproduce on land without dependence on water environments. The amniotic egg contains its own water supply and protects the embryo from desiccation. Scales provide protection but don't enable terrestrial reproduction. Increased size and food availability are not specific adaptations for land reproduction.

Heat generation scales with volume while heat loss scales with surface area. The volume-to-surface-area ratio increases with size (cube-square law), so larger animals retain heat better. Bears have the most favorable ratio among these animals, making them best suited for cold climates.

Amphitrichous: Flagella at both sides or ends, e.g. Nitrosomonas

Urochordata (tunicates) is a subphylum of chordates that includes Herdmania, a sessile marine organism. Amphioxus belongs to Cephalochordata. Petromyzon (lamprey) is a vertebrate. Balanoglossus belongs to Hemichordata, not Chordata.

Shipworms (Teredo) are marine bivalve mollusks that bore into wood using their shells. They belong to class Bivalvia within phylum Mollusca. The other options are other mollusk classes but not the correct one for shipworms.

Glochidium is a parasitic larval stage unique to freshwater bivalves (family Unionidae), which includes mussels. These larvae attach to fish gills as part of their life cycle. Porifera have amphiblastula larvae, Coelenterata have planula larvae, and Echinodermata have bipinnaria and pluteus larvae.

Annelids (segmented worms) are coelomate organisms with a true body cavity. They possess a hydrostatic skeleton, segmentation (metamerism), and metanephridia for excretion. Pseudocoelom is a body cavity type found in nematodes, not annelids, making it the correct 'not a characteristic' answer.

Sponges are not exclusively marine - some species like Spongilla are freshwater inhabitants. Option B contains a typo where 'landform' should be 'larval form' (amphiblastula is a larval stage). The other options are correct: sponges do have calcareous/siliceous spicules and are sessile.

Ascaris (a nematode) has a syncytial epidermis where multiple nuclei exist within a continuous cytoplasmic layer without cell membranes separating them. This is a characteristic feature of nematodes. Hydra has tissue grade organization, earthworms have a cellular epidermis with chloride cells, and starfish (echinoderms) have a different epidermal structure.

Birds are not ectothermic. Animals, such as reptiles, fish or amphibians use environmental energy and behavioral adaptations to regulate their body temperature and are ectothermic. Birds and mammals are endothermic.

Physiological evidence through blood test reveals that turtles are more closely related to crocodiles than to lizards, snakes and mammals. The term turtle is usually used for aquatic or semiaquatic forms and resembles crocodiles in possession of  palate, immovable quadrate, protease, etc.