Human blood is red but in certain situations it can be green, for example in the deep ocean.
The reason is quite simple, you can use the physics knowledge learned in school to explain. According to the knowledge learned, any object we see is due to light reflecting from it and entering our eyes. Objects that absorb other light spectrums, reflecting red light will appear red.
But the reality is a little more complicated, objects typically reflect a range of wavelengths of light. Blood absorbs most colors and reflects light primarily in the red spectrum, with a much smaller amount of green and blue light.
Meanwhile, ocean water appears slightly blue because it absorbs a lot of light at red wavelengths. At a certain depth in the ocean, enough red light is absorbed that only the blue light is reflected back to our eyes, which then appears green. Therefore, human red blood appears green at ocean depths.
Because red light is absorbed very well by water, many species of fish appear red when living at the bottom of the ocean.
At the bottom of the ocean, red and black animals predominate. This is because black animals absorb all available colors of light, while red animals appear black because they have no red light to reflect and their bodies absorb all other available wavelengths of light.
Plan an inclusive virtual Halloween party for remote teams with time-zone-friendly scheduling, simple games, accessible options, and a practical hosting checklist.
Explore seven Halloween team building games for the workplace, with quick rules, hybrid-friendly options, accessibility tips, and practical safety guidance.
Mix a glossy prop-only fake blood batch, choose safer products for skin and costumes, and test cleanup before Halloween night.
Create a gentle Halloween look with pastel colors, friendly ghosts, easy no-carve accents, and practical safety tips for your home.
Create a spooky office cubicle with Halloween desk decor ideas that keep your workspace usable, tidy, and mindful of workplace safety.
Plan a recognizable Halloween 2026 look with pop culture costumes inspired by Spider-Man, Supergirl, Toy Story 5, Moana, Mario, and Wednesday.
Sort leftover Halloween candy safely, share or repurpose sealed treats, and choose food use or compost for pumpkins based on their condition.
Compare workplace Halloween costume choices by respect, dress code, mobility, and safety—and learn when a subtle accessory or a policy check is the better option.
Find a couples costume that fits your style, budget, and comfort level, from Addams Family classics to original inside-joke duos.
Need a last-minute high school Halloween costume? Compare 10 easy closet-based ideas by prep time, comfort, school-day practicality, and simple safety checks.
