Animal Camouflage and Bioluminescence

Animals with larger eyes, making them more visible, are more susceptible to predators.

Non-transparent food makes transparent animals visible to predators. Some transparent animals eat only transparent food to remain hidden.

Squid can change their body shape, skin color using chromatophores, and reflect light using iridophores to blend into their surroundings.

The production and emission of cold light by living organisms. It involves chemical reactions that convert chemical energy into radiant energy.

Fireflies are an example of invertebrates that use bioluminescence.

Bioluminescent organisms are found across the planet, with a majority being marine and residing in deep-sea environments.

While the purpose of bioluminescence in simple organisms like bacteria and fungi is not completely understood, it's crucial for survival and reproduction in many complex organisms.

Many marine creatures including cephalopods, copepods, krill, deep-sea fish, jellyfish, and cone jellyfish exhibit bioluminescence.

BFQ is a measurement of an animal's bite force, determined by muscle fiber arrangement, number, and orientation.

The maximum opening of the jaw, influenced by muscle contraction and relaxation forces, determines the size of prey an animal can consume.

A method of feeding where animals create negative pressure in their mouth to suck in water and prey.

Predators using specialized techniques like tail smacking or electric shocks to stun prey before consuming it.

A camouflage technique where animals have a darker dorsal surface and a lighter ventral surface to blend into the environment.

Light-producing organs found on some deep-sea animals, used for camouflage or attracting prey.

The depth at which the bioluminescent light emitted by an animal matches the downwelling light intensity.

Specialized muscle tissue in electric rays and eels capable of storing and releasing electrical energy.

The ability of an animal to sense electric fields from both biological and artificial sources (like boat engines).

Detecting weak electric fields produced by other organisms. Sharks are masters of this.

Producing electric fields and then sensing how those fields are disrupted by the environment. Some rays do this.

Special sensory organs that detect weak electric fields in sharks and rays. These organs are filled with a conductive gel.

Sharks use electroreception to find prey, navigate, and avoid predators. The abundance of pores varies between species based on their feeding habits.

Human activities like boating generate electric fields that can disrupt sharks' electroreception, potentially affecting their behavior.

The ability of animals to sense and use Earth's magnetic field for navigation. Sharks are believed to possess this sense.

Sharks may use magnetoreception to navigate long distances in open oceans, explaining their ability to swim in straight lines.

Hormones made from amino acids. They bind to receptors on the cell surface, triggering a cascade of events through secondary messengers. This results in fast, but temporary effects.

Hormones derived from cholesterol. They travel through the cell membrane, bind to receptors inside the cell, and then migrate to the nucleus to influence gene expression. This leads to slower but longer-lasting effects.

Precursor molecules that are inactive until cleaved and fragmented into active hormones.

Steroid hormones include progestogens (pregnancy hormones), glucocorticoids (stress hormones), androgens (male hormones), and estrogens (female hormones).

A one-way pathway for the synthesis of steroid hormones, starting from cholesterol and branching to different types of steroid hormones.

Hormones or hormone-related substances in bodily fluids (blood, urine, etc.) that reflect the health and physiological state of an individual or population.

Hormones or hormone-related substances that provide insights into reproductive health of individuals or populations.

Hormones or hormone-related substances that reveal how individuals or populations respond to their environment and changes.

The HPG axis refers to the interaction between the hypothalamus, pituitary gland, and gonads. It plays a crucial role in controlling reproductive processes.

Gonadotropin-releasing hormone (GnRH) is released by the hypothalamus, stimulating the pituitary gland to produce LH and FSH.

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are released by the pituitary gland and act on the gonads (testes or ovaries) to trigger key reproductive processes.

LH and FSH stimulate the release of gametes (eggs or sperm) and drive hormone production in the gonads (e.g., testosterone, estrogen, and progesterone).

Monitoring hormone levels, particularly estrogen, progesterone, and testosterone, provides insights into an animal's reproductive status, including maturity, breeding season, ovulation, and pregnancy.

Hormone levels indicate when an animal becomes sexually mature and capable of reproduction.

Hormone fluctuations reveal the duration of the breeding season, which varies depending on the species and environmental factors.

Increased progesterone levels are a key indicator of pregnancy in females.

North Atlantic right whales are highly sensitive to low-frequency sounds, which can interfere with their communication, disrupt their perception of the environment, and cause stress.

After the 9/11 attacks, the closure of harbors led to a significant decrease in low-frequency boat noise, resulting in lower stress levels in North Atlantic right whales.

Chemicals, both natural and synthetic, that interfere with the body's hormones. These disruptors can mimic or block the actions of hormones.

Agonist disruptors bind to hormone receptors and trigger a response similar to the natural hormone. Antagonist disruptors block receptors, preventing natural hormones from binding.

Endocrine disruptors can interfere with the body's hormonal processes at multiple levels, leading to problems with reproduction, development, and overall health.

Leydig cells produce testosterone, while Sertoli cells nourish developing sperm cells in the testes.

Sand gobies exposed to effluent containing estrogen mimics showed reduced testes development, abnormal reproductive behavior, and even the development of female-like characteristics.

The process of egg yolk production in female animals.