Cephalopod Lower Classifications: Orders and Families Explained
Cephalopoda is a class of marine mollusks that includes nautiluses, cuttlefish, squid, and octopuses. The lower classifications within this class are organized into two extant subclasses, Nautiloidea and Coleoidea, with Coleoidea further divided into the superorders Decapodiformes and Octopodiformes. This article explains the taxonomic ranks below the class level, describes the distinguishing features of each order and family, and provides a practical framework for identifying and recording cephalopod specimens. The content is intended for students, researchers, life-science professionals, and informed general readers who need a structured reference for cephalopod taxonomy.
Taxonomic Framework of Cephalopoda
The phylum Mollusca contains the class Cephalopoda, which is divided into subclasses, superorders, orders, and families. The living cephalopods belong to two subclasses: Nautiloidea, represented by the chambered nautilus, and Coleoidea, which includes all other living cephalopods. The coleoids are distinguished by the internalization or loss of the shell, the presence of arms and tentacles, and advanced sensory and nervous systems.
The subclass Coleoidea is split into two superorders based on arm and tentacle morphology. Decapodiformes possess eight arms and two tentacles, totaling ten appendages. Octopodiformes possess eight arms and lack the two elongated tentacles found in decapods. This fundamental division shapes the classification of all living cephalopod families.
The classification of cephalopods continues to be refined through molecular and morphological studies. Mitochondrial genome analysis has proven valuable for resolving phylogenetic relationships among octopodiform families, as demonstrated in studies of the Amphitretidae family that used 13 protein-coding genes, two ribosomal RNAs, and 22 transfer RNAs from 26 cephalopod mitochondrial genomes (mitochondrial genome analysis of Amphitretidae). Such genetic evidence complements traditional morphological classification and helps clarify the evolutionary relationships between families.
Subclass Nautiloidea
The subclass Nautiloidea contains the externally shelled cephalopods. The only living family within this subclass is Nautilidae, which includes the genera Nautilus and Allonautilus. These animals retain an external coiled shell divided into chambers connected by a siphuncle, a tissue tube that regulates buoyancy.
Nautiloids differ from coleoids in several fundamental ways. They possess numerous simple arms without suckers, lack tentacles, and have a funnel formed by two separate flaps instead of a fused tube. The eyes of nautiloids are simple pinhole-type eyes without lenses, a significant difference from the complex lens eyes of coleoids.
The nautilus shell is divided into internal chambers filled with gas and liquid. The animal occupies the outermost chamber and extends its body into the shell opening. Nautiloids are found in the tropical Indo-Pacific region and typically inhabit deep reef slopes during the day, migrating to shallower waters at night to feed.
Subclass Coleoidea
The subclass Coleoidea encompasses all living cephalopods except the nautiloids. Coleoids have internalized or reduced shells, possess eight or ten appendages, and exhibit the most advanced nervous systems among invertebrates. The subclass is divided into two superorders based on appendage count and arrangement.
Superorder Decapodiformes
Decapodiformes are characterized by eight arms and two tentacles. The tentacles are typically longer than the arms and are retractable into pouches. The tentacles bear suckers only on their distal clubs, which are used to capture prey. This superorder includes squid, cuttlefish, and bobtail squid.
The decapodiform body plan includes a mantle, fins (in most species), a funnel, and a head with large eyes. The internal shell varies among groups, from the rigid cuttlebone of cuttlefish to the reduced gladius or pen of squid and the vestigial shell of bobtail squid.
Superorder Octopodiformes
Octopodiformes possess eight arms and lack the two elongated tentacles of decapods. This superorder includes octopuses, vampire squid, and their relatives. The arms bear suckers along their entire length, and in most species, the arms are connected by a web of tissue at their base.
Octopodiforms exhibit a wide range of body forms, from the muscular benthic octopuses to the gelatinous pelagic species. The internal shell is reduced or absent in most octopodiforms, and the mantle is typically rounded or sac-like.
Order Sepiida
The order Sepiida contains the cuttlefish, a group of decapodiform cephalopods characterized by the presence of a cuttlebone, a porous internal shell that provides buoyancy control. Cuttlefish possess a broad, flattened body with fins running along the entire length of the mantle.
The family Sepiidae is the primary family within this order, containing the genus Sepia and related genera. Cuttlefish are benthic or demersal animals found in coastal waters of the eastern Atlantic, the Mediterranean, and the Indo-Pacific. They are absent from the Southern Ocean, where loliginid squid, sepiids, and sepiolids are not found (Southern Ocean cephalopod fauna).
Cuttlefish are notable for their sophisticated camouflage abilities, which are controlled by chromatophores, iridophores, and leucophores in the skin. The neural control of chromatophore display in cephalopods involves chromatophore lobes in the subesophageal brain, and the speed of response in cephalopods exceeds that of teleost fishes (chromatophore systems in cephalopods and teleosts).
The common cuttlefish, Sepia officinalis, is a well-studied species that serves as a model organism for nitric oxide biology research. The nitric oxide signaling pathway in marine invertebrates has been investigated with special emphasis on Sepia due to the increasing appreciation of cephalopods as valuable model systems (nitric oxide in marine invertebrates).
Order Sepiolida
The order Sepiolida contains the bobtail squid, small decapodiform cephalopods with a rounded mantle and a reduced internal shell. Bobtail squid are typically bottom-dwelling animals found in coastal and shelf waters worldwide, with the exception of the Southern Ocean where sepiolids are absent (Southern Ocean cephalopod fauna).
The families within Sepiolida include Sepiolidae and related groups. These animals are generally small, with most species reaching mantle lengths of less than 10 centimeters. Many bobtail squid harbor bioluminescent bacteria in a specialized light organ within the mantle cavity, which they use for counter-illumination to match downwelling light and avoid predators.
The phylogenetic relationship between Sepiida and Sepiolida has been clarified by fossil discoveries. A fossil sepioid from the Upper Cretaceous of South Dakota, Uluciala rotundata, shows intermediate morphology between the two orders, demonstrating a close relationship and indicating that sepioids experienced an early radiation in the later part of the Late Cretaceous (oldest sepioid cephalopod from the Cretaceous).
Order Myopsida
The order Myopsida contains the inshore squid of the family Loliginidae. These squid possess a cornea covering the eye, a feature that distinguishes them from the open-eyed squid of the order Oegopsida. Myopsid squid are found in coastal and shelf waters of tropical and temperate oceans.
The family Loliginidae includes commercially important genera such as Loligo, Doryteuthis, and Uroteuthis. The veined squid, Loligo forbesii, occurs on European shelf areas including the Azores and represents a valuable resource for the European commercial fishery in the North East Atlantic (phylogeography of the veined squid). Genetic studies of this species using microsatellites and mitochondrial cytochrome oxidase subunit I sequences have identified three main clades and revealed that geographical barriers influence population structure and reduce gene flow (phylogeography of the veined squid).
Myopsid squid are typically neritic species that form schools and are targeted by commercial fisheries. They have a muscular mantle, two fins, and eight arms with two tentacles. The life cycle is generally short, with most species living less than two years.
Order Oegopsida
The order Oegopsida contains the open-ocean squid, a diverse group of families that lack a corneal covering over the eye. This order includes the family Ommastrephidae, which contains the flying squid and arrow squid, and the family Cranchiidae, which contains the glass squid.
Oegopsid squid are predominantly oceanic pelagic species. In the Southern Ocean, all squid species are oceanic pelagic forms, and the family Ommastrephidae contains muscular species with potential for commercial exploitation (Southern Ocean cephalopod fauna). These squid play an important role in the ecology of the Southern Ocean, linking abundant mesopelagic fish and crustaceans with higher predators such as albatross, seals, and whales (Southern Ocean cephalopod fauna).
The family Ommastrephidae includes some of the largest and most commercially valuable squid species, such as the Humboldt squid and the Argentine shortfin squid. These animals are powerful swimmers with a muscular mantle and well-developed fins. They are capable of jet propulsion and some species can glide above the water surface.
Other families within Oegopsida include the Enoploteuthidae, Onychoteuthidae, and Histioteuthidae. These families occupy various ecological niches in the open ocean, from epipelagic to mesopelagic and bathypelagic depths.
Order Octopoda
The order Octopoda contains the octopuses, octopodiform cephalopods with eight arms and no internal shell. This order is divided into two suborders: Incirrata, which contains the benthic and pelagic octopuses with two rows of suckers on each arm, and Cirrata, which contains the finned deep-sea octopuses with one row of suckers and paired cirri alongside each sucker.
Suborder Incirrata
The suborder Incirrata includes the family Octopodidae, which contains the typical benthic octopuses found in coastal waters worldwide. These animals have a rounded mantle, eight arms of equal length, and lack fins. The arms are connected by a web, and the suckers are arranged in one or two rows along each arm.
The family Octopodidae includes the genus Octopus and related genera. These octopuses are solitary, benthic predators that feed on crustaceans, mollusks, and fish. They are notable for their intelligence, problem-solving abilities, and sophisticated camouflage.
The family Argonautidae contains the paper nautiluses, which are pelagic octopuses. The females of this family secrete a thin, coiled shell that is used as a brood chamber, while the males are much smaller and do not produce a shell.
The family Amphitretidae contains pelagic octopuses with a gelatinous body. The complete mitochondrial genomes of two species in this family, Japetella diaphana and Amphitretus pelagicus, have been analyzed to investigate their phylogenetic position within Amphitretidae (mitochondrial genomes of two octopi). The analysis revealed a monophyletic relationship between Bolitaenidae and Vitreledonellidae and a sister taxon relationship between Amphitretidae and Tremoctopodidae (mitochondrial genomes of two octopi).
The family Bolitaenidae contains the gelatinous octopuses found in mesopelagic depths. These animals have a soft, translucent body and are often found in association with jellyfish.
Suborder Cirrata
The suborder Cirrata contains the finned octopuses, which are deep-sea animals with a gelatinous body, two fins, and a web connecting the arms. These octopuses have a U-shaped shell remnant and one row of suckers on each arm, with paired cirri alongside the suckers.
Cirrate octopuses are found at depths ranging from 300 to over 5,000 meters. They are slow-moving animals that use their fins for propulsion and their arms for capturing small prey from the water column or sediment.
Order Vampyromorpha
The order Vampyromorpha contains a single living species, the vampire squid, Vampyroteuthis infernalis. This species is placed in the family Vampyroteuthidae and represents a transitional form between the decapodiform and octopodiform lineages.
The vampire squid possesses eight arms connected by a web, but it also has two small retractable filaments that are considered derived from tentacles. The animal is found in mesopelagic depths worldwide and is adapted to low-oxygen environments.
The vampire squid has a gelatinous body, large eyes, and is covered with photophores that produce bioluminescent displays. It feeds on marine snow and small particles instead of active prey.
At a Glance
The following table summarizes the key characteristics of the major cephalopod orders and their families.
| Order | Representative Families | Appendages | Shell | Habitat | Example Species |
|---|---|---|---|---|---|
| Nautilida | Nautilidae | Numerous simple arms | External coiled shell | Tropical reef slopes | Nautilus pompilius |
| Sepiida | Sepiidae | 8 arms, 2 tentacles | Internal cuttlebone | Coastal benthic | Sepia officinalis |
| Sepiolida | Sepiolidae | 8 arms, 2 tentacles | Reduced internal shell | Coastal benthic | Euprymna scolopes |
| Myopsida | Loliginidae | 8 arms, 2 tentacles | Internal gladius | Coastal and shelf | Loligo forbesii |
| Oegopsida | Ommastrephidae, Cranchiidae | 8 arms, 2 tentacles | Internal gladius | Oceanic pelagic | Dosidicus gigas |
| Octopoda | Octopodidae, Argonautidae, Amphitretidae | 8 arms | Reduced or absent | Benthic and pelagic | Octopus vulgaris |
| Vampyromorpha | Vampyroteuthidae | 8 arms, 2 filaments | Reduced | Mesopelagic | Vampyroteuthis infernalis |
Practical Identification Workflow
Identifying a cephalopod specimen to the family level requires a systematic approach that examines multiple morphological features. The following workflow provides a structured method for classification.
Step 1: Count the Appendages
Determine whether the specimen has eight or ten appendages. If the specimen has ten appendages, with two being longer tentacles, it belongs to the Decapodiformes. If it has eight arms without elongated tentacles, it belongs to the Octopodiformes.
Step 2: Examine the Shell
If an external coiled shell is present, the specimen belongs to the Nautilidae family. If the shell is internal, examine its structure. A rigid, porous cuttlebone indicates the order Sepiida. A reduced or vestigial shell indicates Sepiolida or Octopoda. A gladius or pen indicates Myopsida or Oegopsida.
Step 3: Assess the Eye Structure
For decapodiforms, determine whether a cornea covers the eye. A closed eye with a corneal covering indicates the order Myopsida. An open eye without a cornea indicates the order Oegopsida.
Step 4: Examine the Fins
The presence and position of fins provide useful taxonomic information. Cuttlefish have fins running along the entire mantle length. Bobtail squid have rounded fins. Myopsid and oegopsid squid have terminal fins. Octopuses in the suborder Incirrata lack fins, while those in the suborder Cirrata possess fins.
Step 5: Record the Sucker Arrangement
Examine the arrangement of suckers on the arms. Octopodiforms typically have one or two rows of suckers. Cirrate octopuses have one row with paired cirri. Incirrate octopuses have one or two rows without cirri.
Records and Measurements
Accurate record keeping is essential for taxonomic work and for studies that use cephalopod specimens. The following measurements and observations should be recorded for each specimen.
Mantle Length
Measure the dorsal mantle length from the anterior mantle edge to the posterior tip of the mantle. This measurement is the standard size metric for cephalopods and is used in fisheries management and ecological studies.
Weight
Record the total body weight and, when possible, the eviscerated weight. Weight data are used to calculate condition indices and to estimate biomass in ecological surveys.
Beak Morphology
The cephalopod beak is a reliable material for species classification. Geometric morphometric approaches have demonstrated that the shape of the beak lateral profile carries phylogenetic signal and that the overall shape parameters of the upper and lower beak are useful for species identification (geometric morphometrics of cephalopod beaks). The shapes of the upper and lower beak show a strong phylogenetic signal, and phenograms based on beak shape reflect the taxonomic positions of families (geometric morphometrics of cephalopod beaks).
For species identification, the lower beak provides better results than the upper beak. Machine learning analysis of beak images has shown that deep features extracted from lower beak images achieve higher classification accuracy than traditional morphometric features (cephalopod species identification using machine learning).
Reproductive Condition
Record the maturity stage of the specimen using a standardized maturity scale. Southern Ocean cephalopods appear to be semelparous, with growth rates probably lower and longevity greater than temperate counterparts (Southern Ocean cephalopod fauna). Eggs are generally large and fecundity low, with putative long development times (Southern Ocean cephalopod fauna).
Collection Location and Depth
Record the geographic coordinates, depth, and habitat type for each specimen. This information is essential for understanding species distributions and for interpreting genetic and morphological data.
Common Failure Patterns in Identification
Several common errors can lead to incorrect cephalopod identification. Awareness of these failure patterns improves the reliability of taxonomic work.
Confusing Tentacles with Arms
The distinction between arms and tentacles is fundamental to cephalopod classification. Tentacles are longer than arms, are retractable, and bear suckers only on the distal club. Arms bear suckers along their entire length. Misidentifying the two elongated tentacles of a decapodiform as arms leads to incorrect classification.
Overlooking the Eye Covering
The presence or absence of a corneal covering over the eye distinguishes Myopsida from Oegopsida. This feature can be difficult to observe in preserved specimens, and the cornea may become opaque or damaged during preservation.
Misinterpreting the Internal Shell
The internal shell varies considerably among cephalopod groups. The cuttlebone of Sepiida is rigid and porous. The gladius of squid is a flexible, feather-shaped structure. The shell of Sepiolida is reduced to a thin plate. The shell of Octopoda is reduced to small stylets or is absent. Misidentifying these structures leads to errors at the order level.
Relying on Color Patterns
Color patterns are unreliable for identification in preserved specimens because chromatophore pigments degrade after death. Live color patterns can be useful for species identification but should be documented with photographs before preservation.
Welfare and Safety Context
Cephalopod research and handling require attention to animal welfare and human safety. Cephalopods are recognized as sentient animals in many jurisdictions, and research involving them may require ethical approval.
Handling Live Cephalopods
Live cephalopods should be handled with care to minimize stress. Squid and cuttlefish may ink when disturbed, and octopuses may bite if threatened. The beak of a large octopus or squid can inflict a painful bite, and some species may inject venom.
Anesthesia and Euthanasia
Anesthesia and euthanasia methods for cephalopods should follow institutional guidelines and applicable regulations. Magnesium chloride is commonly used for anesthesia, but specific protocols should be developed in consultation with veterinary professionals and institutional animal care committees.
Parasite Awareness
Cephalopods host a variety of parasites, including dicyemids, which are found primarily in the renal organs of coleoid cephalopods (cryptic diversity in dicyemid parasites). Amplicon sequencing has revealed that current species classifications may underestimate the true diversity of dicyemids, with geographic location and host species being significant determinants of dicyemid community composition (cryptic diversity in dicyemid parasites). Researchers handling cephalopod renal tissues should be aware of these parasites.
Limitations of Current Classification
The classification of cephalopods at the family level and below remains an active area of research. Several limitations affect the current taxonomic framework.
Incomplete Fossil Record
The fossil record of soft-bodied cephalopods is incomplete, which limits understanding of evolutionary relationships. Mineralized belemnoid cephalic cartilage from the late Triassic Polzberg Konservat-Lagerstatte provides rare evidence of cartilaginous structures in fossil cephalopods (mineralized belemnoid cephalic cartilage). The biochemical composition of recent cephalopod cartilage differs from vertebrate cartilage, but histologically the cartilages of these animal groups resemble one another remarkably (mineralized belemnoid cephalic cartilage).
Cryptic Diversity
Molecular studies have revealed cryptic diversity within morphologically defined species. The dicyemid parasites of coleoid cephalopods show higher genetic diversity than morphology-based taxonomy suggests, and similar patterns may exist in the cephalopod hosts themselves (cryptic diversity in dicyemid parasites).
Ongoing Phylogenetic Revision
Phylogenetic relationships among cephalopod families continue to be revised as new molecular data become available. Mitochondrial genome analysis has resolved some relationships but has also revealed unexpected groupings. The phylogenetic position of the Amphitretidae family, for example, has been clarified by mitochondrial genome analysis, which revealed a sister taxon relationship between Amphitretidae and Tremoctopodidae (mitochondrial genomes of two octopi).
Extinct Groups
The classification of extinct cephalopod groups presents additional challenges. Heteromorph ammonoids, which formed conchs with detached whorls or non-planispiral coiling, appeared convergently four times within this extinct group (heteromorph ammonoid palaeobiology). Based on phylogenetic bracketing with nautiloids and coleoids, heteromorphs had 10 arms, a well-developed brain, lens eyes, a buccal mass with a radula, and ammonia in their soft tissue (heteromorph ammonoid palaeobiology).
Professional Escalation Criteria
Taxonomic identification should be escalated to a specialist when certain conditions are met. The following criteria indicate when professional expertise is needed.
Ambiguous Morphological Features
If a specimen exhibits morphological features that do not clearly match any known family, escalate to a cephalopod taxonomist. This situation may indicate an undescribed species or a specimen with atypical morphology.
Geographic Range Extensions
If a specimen is collected outside its known geographic range, confirm the identification with a specialist. Range extensions may indicate climate-driven distribution shifts or misidentification.
Molecular Confirmation Needs
When morphological identification conflicts with molecular data, or when species-level identification is required for research or management purposes, escalate to a specialist who can perform genetic analysis.
Commercial or Regulatory Implications
If identification is required for fisheries management, trade regulation, or conservation decisions, escalate to a qualified taxonomist. Misidentification can have significant economic and regulatory consequences.
Frequently Asked Questions
What is the difference between Decapodiformes and Octopodiformes?
Decapodiformes have eight arms and two tentacles, totaling ten appendages. Octopodiformes have eight arms and lack the elongated tentacles. The tentacles of decapodiforms are retractable and bear suckers only on their distal clubs, while the arms of octopodiforms bear suckers along their entire length.
How many families are in the class Cephalopoda?
The number of families within Cephalopoda varies depending on the taxonomic authority consulted. Living cephalopods are distributed across approximately 40 to 50 families, with the exact count subject to ongoing phylogenetic revision. The families are distributed across the subclasses Nautiloidea and Coleoidea, with the majority belonging to the coleoid orders.
What is the difference between a cuttlebone and a gladius?
A cuttlebone is the rigid, porous internal shell of cuttlefish in the order Sepiida. It provides buoyancy control and is composed of calcium carbonate. A gladius is the flexible, feather-shaped internal shell of squid in the orders Myopsida and Oegopsida. The gladius is composed of chitin and provides structural support for the mantle muscles.
Are all octopuses in the same family?
No, octopuses are distributed across multiple families within the order Octopoda. The family Octopodidae contains the typical benthic octopuses. Other families include Argonautidae, which contains the paper nautiluses, Amphitretidae, which contains gelatinous pelagic octopuses, and Bolitaenidae, which contains gelatinous mesopelagic octopuses. The suborder Cirrata contains the finned deep-sea octopuses in families such as Opisthoteuthidae and Cirroteuthidae.
What is the vampire squid classified as?
The vampire squid, Vampyroteuthis infernalis, is classified in the order Vampyromorpha and the family Vampyroteuthidae. It is the only living species in this order. The vampire squid has eight arms connected by a web and two small retractable filaments that are considered derived from tentacles.
How do scientists identify cephalopod species from beaks?
Cephalopod beaks are reliable materials for species classification. Geometric morphometric approaches analyze the shape of the beak lateral profile, and the overall shape parameters of the upper and lower beak are useful for species identification (geometric morphometrics of cephalopod beaks). Machine learning approaches using deep features extracted from beak images can achieve high classification accuracy, with lower beaks providing better results than upper beaks (cephalopod species identification using machine learning).
Are cephalopods found in the Southern Ocean?
Yes, the Southern Ocean has a distinctive cephalopod fauna with high levels of endemism in the squid and particularly in the octopodids (Southern Ocean cephalopod fauna). Loliginid squid, sepiids, and sepiolids are absent from the Southern Ocean, and all the squid are oceanic pelagic species (Southern Ocean cephalopod fauna). The octopodids dominate the neritic cephalopod fauna, with high levels of diversity probably associated with niche separation (Southern Ocean cephalopod fauna).
What is the earliest known cephalopod fossil?
A potential cephalopod fossil from the early Cambrian of eastern Newfoundland, Canada has been reported in Communications Biology (potential cephalopod from the early Cambrian). This finding, if confirmed, would extend the fossil record of cephalopods into the early Cambrian period.
Related Articles
References and Further Reading
- NCBI Literature Resources. National Center for Biotechnology Information.
- PubMed. National Library of Medicine.
- Southern Ocean cephalopods.. Advances in marine biology, 2006.
- Geometric morphometrics casts light on phylogenetic relevance of cephalopod beak morphological.. Journal of morphology, 2024.
- Recent advances in heteromorph ammonoid palaeobiology.. Biological reviews of the Cambridge Philosophical Society, 2021.
- Mineralized belemnoid cephalic cartilage from the late Triassic Polzberg Konservat-Lagerstätte (Austria).. PloS one, 2022.
- Chromatophore systems in teleosts and cephalopods: a levels oriented analysis of convergent systems.. Brain, behavior and evolution, 1992.
- Phylogeography of the veined squid, Loligo forbesii, in European waters.. Scientific reports, 2022.
- Nitric oxide in marine invertebrates: a comparative perspective.. Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, 2005.
- Cephalopod species identification using integrated analysis of machine learning and deep learning approaches.. PeerJ, 2021.
- Cephalopod Genome Expansion Drives Broader Reflectin Domain Boundaries. 2026.
- Decoding thermal adaptation: genome-wide identification of TRP channel repertoire in cephalopods and gene expression responses to chronic thermal exposure in <,i>,Sepia officinalis<,/i>, and <,i>,Octopus maya<,/i>, embryos.. 2026.
- The Complete Mitochondrial Genomes of Two Octopi of the Western Pacific Ocean, <,i>,Japetella diaphana<,/i>, and <,i>,Amphitretus pelagicus<,/i>, (Cephalopoda: Amphitretidae), and Their Phylogenetic Position Within Amphitretidae.. 2026.
- Amplicon sequencing reveals the cryptic diversity in the dicyemid parasites of coleoid cephalopods sampled from the Atlantic and Pacific Oceans.. 2026.
- A non-invasive method to genotype cephalopod sex by quantitative PCR.. 2026.
- The oldest sepioid cephalopod from the Cretaceous discovered by Digital fossil-mining with zero-shot learning AI.. 2026.
- A potential cephalopod from the early Cambrian of eastern Newfoundland, Canada. Communications Biology, 2021.
This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.