Animal Crossword Puzzle

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Across
  1. 3. - an internal, gas-filled organ in most bony fish (Osteichthyes) located in the dorsal portion of the body cavity that primarily acts as a hydrostatic organ to regulate buoyancy
  2. 6. - a hard, external protective and supportive covering located on the outside of an invertebrate's body, secreted by the epidermis
  3. 8. - a temporary feto-maternal organ formed by the apposition or fusion of fetal (or embryonic) membranes to the maternal uterine mucosa to facilitate physiological exchange
  4. 10. - a body plan where an organism can be divided into matching left and right mirror-image halves along a single, central sagittal plane running from its front (anterior) to its back (posterior)
  5. 14. - a form of asexual reproduction where a new organism develops from an outgrowth or bud on the parent organism due to cell division at a specific site
  6. 15. - a tough, flexible, semi-transparent connective tissue that makes up the entire internal skeleton
  7. 17. - the specialized, milk-producing exocrine glands (modified sweat glands) found in marine mammals
  8. 19. - a self-contained, air-breathing egg featuring a protective shell and specialized extra-embryonic membranes that nourish and shield the embryo, allowing reproduction away from open water
  9. 20. - a unique hydraulic network of fluid-filled canals and muscular appendages found exclusively in marine animals of the phylum Echinodermata
  10. 21. - an organism that generates and maintains its internal body heat primarily through high metabolic activity rather than relying on the surrounding water temperature
Down
  1. 1. - the biological process where an organism periodically sheds and replaces its outer covering—such as a hard exoskeleton, shell, or skin—to allow for physical growth, repair, or seasonal renewal
  2. 2. - animals belonging to the subphylum Vertebrata that possess a backbone, a skull, and an internal skeleton while living all or a significant part of their lives in saltwater environments
  3. 4. - animals that don’t have a backbone or veritable column
  4. 5. - an abnormal growth of tissue that sticks out from the surface of a mucous membrane into a hollow space or body cavity
  5. 7. - an organism that relies primarily on external environmental sources of heat rather than internal metabolic processes to regulate its body temperature
  6. 9. - an organism that possesses both functional male and female reproductive organs—or can change between sexes—during its lifetime
  7. 11. - the free-swimming, umbrella- or bell-shaped body form typical of animals in the phylum cnidaria commonly known as a jellyfish.
  8. 12. - the lack or absence of symmetry, where two sides, halves, or parts of something do not match in shape, size, or arrangement
  9. 13. - an internal structural frame made of mineralized tissue, bone, cartilage, or calcium carbonate plates that sits beneath an animal's soft tissues
  10. 16. - an arrangement of similar body parts, shapes, or patterns around a central axis
  11. 18. - the ecological region at the very lowest level of a body of water, including the sediment surface and sub-surface layers of the ocean, sea, lake, or river floor